The expression you entered has a field, control, or property name that Microsoft access can’t find

I have the following statement; When I open the db I get the following error:

"The expression you entered has a field, control, or property name that Microsoft access can’t find"

I can't seem to find what is wrong with it?

Any help is much appreciate



Private Sub Form_Current()
 
If Not IsNull(Me.DatSowd) Then
Me.WkGoal = DLookup("WkGoal", "tblSS", "ISNo='" & Me.ISNo & "' And DatSowd=#" & Me.DatSowd & "#")
End If
 
End Sub