Reference field on form

I had this line
GBL_Tab05ID = Me.Tab05ID

and wanted to change this. I have this on the On Current event and it gives me an error because the data is not in the record source when the form opens. How can I change the me. to the formname? The form gets dynamically created so i have

Dim CurrentForm As String
CurrentForm = Me.Form.Name

then i put

GBL_Tab05ID = Forms(CurrentForm).Form.Tab05ID

but that did not work...what is the correct syntax?

Reference field on form