Sub routine problem when used with Detail_Click event and error 2166

I have a strange problem were a sub routine operates differently when called from two different events.
I have sProcessPOID that is being called from a keypress event and the detail_click event of the form. Code works fine when called from the keypress event but not the click.

This is a typical PO form and the sub basicly is performing as a lostfocus or exit handler for tbPOID. I'm not using the actual built in events because I don't want the exit code to run in certain situations such as if the user clicked the "Exit" button while textbox has focus.

There are 3 ways of exiting the texbox, Tab, Return, and clicking into the Details portion of the form where I have a tab control. When the user does this tbPOID can have 3 possible conditions:

It's Null or Empty - msgbox the user to enter a value
"P" this a placeholder saying we're starting a new record and we'll get the next sequencial number on Save.
Any other value - go see if this is a existing PO, if so goto that record. If not msgbox the user and make sure they want to start a new record using the value entered.

When called from the click event the value of tbPOID seems to be magically set to "P" which causes the error 2166. I'm fairly sure the value isn't really getting changed to "P".

I can enter existing PO "P2001", trigger the click event, it fails,  click "OK" on the error message, the textbox gets focus again with "P2001" still showing so I  Tab/Return out without changing anything and the code runs as expected.

Here is the results of my debug:

Detail_Click() Results
-------------------------
--tbPOID value was "P"
Detail Click
tbPOID = P
Post Processing

--tbPOID value was Empty "" 
Detail Click
tbPOID = P
Post Processing
Error 2166: You can't lock a control while it has unsaved changes.

--tbPOID value was "P2001" a valid existing record
Detail Click
tbPOID = P
Post Processing
Error 2166: You can't lock a control while it has unsaved changes.

tbPOID_KeyPress Results
-------------------------
--tbPOID value was "P"
tbPOID = P
Post Processing

--tbPOID value was Empty ""
tbPOID =
Null Value
(Message box code ran fine)

--tbPOID value was "P2001" a valid existing record
tbPOID = P2001
Match Found
Post Processing

I even cut/pasted the exact same code into a button event and it worked perfect so something is happening in conjuction with the detail click event but I don't have a clue what. TIA
-Ralph

Private Sub tbPOID_KeyPress(KeyAscii As Integer)
   On Error GoTo err_Handler
   LimitFieldSize KeyAscii, ELookup("LengthLimit", "tblVoucher", "Voucher = 'P'")
   KeyAscii = UpperCaseText(KeyAscii)
   Select Case KeyAscii
   Case 9, 13   'Tab or Return ie. Exiting the Textbox so process content before moving focus
      sProcessPOID
   End Select
exit_Handler:
   Exit Sub
err_Handler:
   Call LogError(Err.Number, Err.Description, Me.Form.Name & " tbPOID_KeyPress", , True)
   Resume exit_Handler
End Sub

Private Sub Detail_Click()
   On Error GoTo err_Handler
   'If the POID box is unlocked we need to process the contents before moving focus
   If Not Me.tbPOID.Locked Then
      Debug.Print "Detail Click"
      sProcessPOID
   End If

exit_Handler:
   Exit Sub
err_Handler:
   Call LogError(Err.Number, Err.Description, Me.Form.Name & " Detail_Click", , True)
   Resume exit_Handler
End Sub

Private Sub sProcessPOID()
   On Error GoTo err_Handler
   Dim strMsg, iResponse As String
   Dim rs As Recordset

   Debug.Print "tbPOID = " & Me.tbPOID

   'Deal with nulls and empty then evaluate real values
   If Nz(Me.tbPOID, "") = "" Then
      Debug.Print "Null Value"
      iResponse = MsgBox("Please enter a PO number", vbExclamation + vbOKOnly, "Enter PO")
      Exit Sub
   End If

   If Me.tbPOID <> "P" Then
      Set rs = Forms!frm_PO.RecordsetClone
      rs.FindFirst "[POID] = '" & Me.tbPOID & "'"
      If rs.NoMatch Then
         Debug.Print "No Match"
         strMsg = "You entered '" & Me.tbPOID & "' as a new PO." & _
         vbCrLf & "Is this correct?"
         iResponse = MsgBox(strMsg, vbQuestion + vbYesNo, "New Order?")
         If iResponse = vbNo Then
            With Me.tbPOID
               .SetFocus
               .SelStart = 0
               .SelLength = Len(.Text)
            End With
            Exit Sub
         End If
      Else
         Debug.Print "Match Found"
         Me.Undo
         Forms!frm_PO.Bookmark = rs.Bookmark
         rs.Close
      End If
   End If

   Debug.Print "Post Processing"
   sLockPOID
   Me.TabPO.Enabled = True
   Me.cbCompany.SetFocus

exit_Handler:
   Exit Sub
err_Handler:
   Call LogError(Err.Number, Err.Description, Me.Form.Name & "Sub: sProcessPOID", , True)
   Resume exit_Handler
End Sub

Private Sub sLockPOID()
   Me.tbPOID.Locked = True
   Me.tbPOID.BackColor = RGB(230, 228, 226)
End Sub

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PO-Form.png