Private Sub PostReasonCodes_Click()

Dim strSQL As String
Dim str2SQL As String
Dim rst As Recordset
Dim MO As String
Dim WO As Long
Dim ReasonCodeVar As String

If Me.Dirty Then Me.Dirty = False

answer = MsgBox("Are you sure you would like to post the new reason codes dates to the system?", 4, "Verify")
If answer = vbYes Then

On Error GoTo Err_PostReasonCodes_Click

'SQL statement to get WO/MO, Reason Code and group, sorted by the WO then MO
strSQL = "SELECT STRUDEX_PRP010.[PRCTL#], [STRUDEX_PRP010]![PRCMPY] & [STRUDEX_PRP010]![PRORD#] AS MO " & _
"FROM (WO_Schedule INNER JOIN STRUDEX_PRP010 ON WO_Schedule.[WO#] = STRUDEX_PRP010.[PRCTL#]) INNER JOIN STRUDEX_OPL010B ON " & _
"(STRUDEX_PRP010.PROLNE = STRUDEX_OPL010B.O1LINE) AND (STRUDEX_PRP010.[PRORD#] = STRUDEX_OPL010B.[O1ORD#]) AND (STRUDEX_PRP010.PRCMPY = STRUDEX_OPL010B.O1CMPY) " & _
"GROUP BY STRUDEX_PRP010.[PRCTL#], [STRUDEX_PRP010]![PRCMPY] & [STRUDEX_PRP010]![PRORD#] ORDER BY STRUDEX_PRP010.[PRCTL#], [STRUDEX_PRP010]![PRCMPY] & [STRUDEX_PRP010]![PRORD#]"

'Opens the data read only as we dont need to change it
Set rst = CurrentDb.OpenRecordset(strSQL, dbOpenSnapshot)

If rst.RecordCount > 0 Then
rst.MoveFirst
WO = rst![PRCTL#]
MO = rst![MO]
Forms!WOs_MOs!ReasonCode.SetFocus
ReasonCodeVar = IIf(IsNull(ReasonCode.Text), "N/A", ReasonCode.Text)
'Checks to see if the Reason Code has been selected
If ReasonCodeVar = "N/A" Then
MsgBox (WO + "" + "does not have a reason code assigned to it, processing aborted")
On Error GoTo Err_Reason_Code_Not_Assigned
End IfEnd If

'Terminates the run of the program
Exit_PostReasonCodes_Click:
Exit Sub

'Error occurs if Reason code field is blank when user posts reason code
Err_Reason_Code_Not_Assigned:
MsgBox ("Data Error 01")
Resume Exit_PostReasonCodes_Click

'General Error
Err_PostReasonCodes_Click:
MsgBox Err.Description
Resume Exit_PostReasonCodes_Click
End If
End Sub

if the value could be null then test for null

incidentally I'd be cautious using + as the string concatenation operator. AFAIK the correct concatenation symbol is &. using + can cuase odd problems if you are concatenating numeric symbols

Thank you, that works but it does not invoke the GO to Error command, is it because it is not in the IF Statement?

Regards,
Dude

how do you expect it to invoke the GO to Error statement
you set an error trap but don't run any code which could cause the error trap to trigger

So where would you put it?

Sorry Im not certain what you intend doing
the way to on error statement works is
you place it before a block of code where you think . expect an error may occur. if an error does arise, code jumps to teh specified code block.

with your code
you set an error trap, but there is no code running after that that could contain an error s the next (effective) statement is exit sub

so basedon your current code the on error is redundant
you may want to review your code and work out what you want to do in the light of that