Is Me.txtRefPull a number type or text type field?
I modified your code a little
Code:
Private Sub cmdPullUp_Click()
Dim validCredentials As Integer
Dim ID As Integer
'On Error GoTo ErrHandler:
If IsNull(Me.txtRefPull) Then
MsgBox "Please Enter Reference Number"
Me.txtRefPull.SetFocus
Exit Sub
End If
validCredentials = DCount("[Ref Num]", "[tbl_Counter_Log]", "[Ref Num] = " & Me.txtRefPull & "")
If validCredentials >= 1 Then
ID = DLookup("[Ref Num]", "tbl_Counter_Log", "[Ref Num] = " & Me.txtRefPull & "")
DoCmd.Close
DoCmd.OpenForm "Counter Log", , , "[Ref Num] = " & ID
Exit Sub
Else
MsgBox "No Record Is Associated With The Reference Number Provided", vbExclamation, "Notification"
Me.txtFilter.SetFocus
Exit Sub
End If
ExitHere:
Exit Sub
ErrHandler:
MsgBox "Unable To Authenticate At This Time. Contact System Administrator For Help."
Me.txtFilter.SetFocus
Resume ExitHere
End Sub