diff --git a/LSL2/STPROC/REACTOR_SERVICES.txt b/LSL2/STPROC/REACTOR_SERVICES.txt
index 5e68fb5..6ab26cb 100644
--- a/LSL2/STPROC/REACTOR_SERVICES.txt
+++ b/LSL2/STPROC/REACTOR_SERVICES.txt
@@ -3577,37 +3577,45 @@ end service
 Service GetReactorsWithDownLLByDtm(DtmToCheck, ReactType)
     
     ErrMsg = ''
-    AllReactors = Reactor_Services('GetReactorNumbers', ReactType)
     SLLReactors = ''
-    If AllReactors NE '' then
-        for each ReactNo in AllReactors using @FM
-            PickPlaceFlag = XLATE('REACTOR', ReactNo, REACTOR_PICK_PLACE$, 'X')
-            If PickPlaceFlag then
-                Open 'DICT.REACT_LL' to DictReactLL then
-                    SearchString = ''
-                    SearchString := 'REACT_NO':@VM:ReactNo:@FM
-                    ReactLLKeys = ''
-                    Btree.Extract(SearchString, 'REACT_LL', DictReactLL, ReactLLKeys)
-                    
-                    For each ReactLLKey in ReactLLKeys using @VM
-                        ReactLLRec = Database_Services('ReadDataRow', 'REACT_LL', ReactLLKey, True$, 0, False$)
-                        ReactLLStartDTM = Field(ReactLLKey, '*', 2)
-                        ReactLLEndDTM = ReactLLRec<REACT_LL_STOP_DTM$>
-                        ReactLLApplicable = false$
-                        If ReactLLStartDTM LE DtmToCheck AND (ReactLLEndDTM EQ '' OR ReactLLEndDtm GT DtmToCheck) then
-                            Locate ReactNo in SLLReactors using @VM setting iPos else
-                                SLLReactors<1, -1> = ReactNo
-                            end
-                        end    
+    If DtmToCheck NE '' then
+        AllReactors = Reactor_Services('GetReactorNumbers', ReactType)
+        If AllReactors NE '' then
+            for each ReactNo in AllReactors using @FM
+                PickPlaceFlag = XLATE('REACTOR', ReactNo, REACTOR_PICK_PLACE$, 'X')
+                If PickPlaceFlag then
+                    Open 'DICT.REACT_LL' to DictReactLL then
+                        SearchString = ''
+                        SearchString := 'REACT_NO':@VM:ReactNo:@FM
+                        ReactLLKeys = ''
+                        Btree.Extract(SearchString, 'REACT_LL', DictReactLL, ReactLLKeys)
                         
-                    Next ReactLLKey
-                end else
-                    ErrMsg = 'Unable to open the REACT_LL dictionary.'
+                        For each ReactLLKey in ReactLLKeys using @VM
+                            ReactLLRec = Database_Services('ReadDataRow', 'REACT_LL', ReactLLKey, True$, 0, False$)
+                            ReactLLStartDTM = Field(ReactLLKey, '*', 2)
+                            ReactLLEndDTM = ReactLLRec<REACT_LL_STOP_DTM$>
+                            ReactLLApplicable = false$
+                            If ReactLLStartDTM LE DtmToCheck AND (ReactLLEndDTM EQ '' OR ReactLLEndDtm GT DtmToCheck) then
+                                Locate ReactNo in SLLReactors using @VM setting iPos else
+                                    SLLReactors<1, -1> = ReactNo
+                                end
+                            end    
+                            
+                        Next ReactLLKey
+                    end else
+                        ErrMsg = 'Unable to open the REACT_LL dictionary.'
+                    end
                 end
-            end
-        Next ReactNo
+            Next ReactNo
+        end else
+            ErrMsg = 'No Reactor IDs found!'
+        end
     end else
-        ErrMsg = 'No Reactor IDs found!'
+        ErrMsg = 'Datetime to check variable was null.'
+    end
+    
+    If ErrMsg NE '' then
+        Error_Services('Add', ErrMsg)
     end
     
     Response = SLLReactors
diff --git a/LSL2/STPROC/REPORTS_API.txt b/LSL2/STPROC/REPORTS_API.txt
index 0776e02..79131b6 100644
--- a/LSL2/STPROC/REPORTS_API.txt
+++ b/LSL2/STPROC/REPORTS_API.txt
@@ -141,7 +141,12 @@ CreateHALItem:
             //Single Load Lock Report from Metrology Services
             ReportStartDtm = Http_Services('GetQueryField', 'StartDate')
         	ReportEndDtm = Http_Services('GetQueryField', 'EndDate')
-            RepJson = Report_Services('GetSLLReportJson', ReportStartDtm, ReportEndDtm)
+        	If ReportStartDtm NE '' AND ReportEndDtm NE '' then
+        	    RepJson = Report_Services('GetSLLReportJson', ReportStartDtm, ReportEndDtm)
+        	end else
+        	    Error_Services('Add', 'Missing parameters for report.')
+        	end
+            
         Case Otherwise$
             Error_Services('Add', 'Unsupported report')
     End Case
diff --git a/LSL2/STPROC/REPORT_SERVICES.txt b/LSL2/STPROC/REPORT_SERVICES.txt
index 7519724..56218f5 100644
--- a/LSL2/STPROC/REPORT_SERVICES.txt
+++ b/LSL2/STPROC/REPORT_SERVICES.txt
@@ -2379,26 +2379,35 @@ Service GetSLLReportJson(FromDt, ToDt)
     ErrorMessage = ''
     SLLReportJson = ''
     objSLLReportJson = ''
+    If FromDt NE '' OR ToDt NE '' then
+        If SRP_Json(objSLLReportJson, 'New', 'Array') then
+            For StartDt = FromDt to ToDt
+                ThisDate = Date_Services('ConvertDateTimeToISO8601', StartDt)
+                ThisDtASMDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'ASM')
+                ThisDtASMPlusDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'ASM+')
+                ThisDtHTRDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'HTR')
+                ThisDtASMDownLLCount = DCount(ThisDtASMDownLL, @VM) + DCount(ThisDtASMPlusDownLL, @VM)
+                ThisDtHTRDownLLCount = DCount(ThisDtHTRDownLL, @VM)
+                objSLLDay = ''
+                If SRP_Json(objSLLDay, 'New', 'Object') then
+                    SRP_Json(objSLLDay, 'SetValue', 'Date', ThisDate)
+                    SRP_Json(objSLLDay, 'SetValue', 'ASM', ThisDtASMDownLLCount)
+                    SRP_Json(objSLLDay, 'SetValue', 'HTR', ThisDtHTRDownLLCount)
+                    SRP_Json(objSLLReportJson, 'Add', objSLLDay)
+                    SRP_Json(objSLLDay, 'Release')
+                end
+            Next StartDt
+            SLLReportJson = SRP_Json(objSLLReportJson, 'Stringify', 'Fast')
+            SRP_Json(objSLLReportJson, 'Release')
+        end else
+            ErrorMessage = 'Error creating the root JSON for the report.'
+        end
+    end else
+        ErrorMessage = 'From Date or To Date was null.'
+    end
     
-    If SRP_Json(objSLLReportJson, 'New', 'Array') then
-        For StartDt = FromDt to ToDt
-            ThisDate = Date_Services('ConvertDateTimeToISO8601', StartDt)
-            ThisDtASMDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'ASM')
-            ThisDtASMPlusDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'ASM+')
-            ThisDtHTRDownLL = Reactor_Services('GetReactorsWithDownLLByDtm', StartDt + 1, 'HTR')
-            ThisDtASMDownLLCount = DCount(ThisDtASMDownLL, @VM) + DCount(ThisDtASMPlusDownLL, @VM)
-            ThisDtHTRDownLLCount = DCount(ThisDtHTRDownLL, @VM)
-            objSLLDay = ''
-            If SRP_Json(objSLLDay, 'New', 'Object') then
-                SRP_Json(objSLLDay, 'SetValue', 'Date', ThisDate)
-                SRP_Json(objSLLDay, 'SetValue', 'ASM', ThisDtASMDownLLCount)
-                SRP_Json(objSLLDay, 'SetValue', 'HTR', ThisDtHTRDownLLCount)
-                SRP_Json(objSLLReportJson, 'Add', objSLLDay)
-                SRP_Json(objSLLDay, 'Release')
-            end
-        Next StartDt
-        SLLReportJson = SRP_Json(objSLLReportJson, 'Stringify', 'Fast')
-        SRP_Json(objSLLReportJson, 'Release')
+    If ErrorMessage NE '' then
+        Error_Services('Add', ErrorMessage)
     end
     
     Response = SLLReportJson