Pete,
A couple of pre-requisites to allow this to work:
(a) The form must be open when you attempt to call the procedure.
(b) The AfterUpdate procedure must be defined as PUBLIC, as opposed to PRIVATE, in order for it to have scope outside of the form. To do this, go into the code behind the form and change the line:
Private Sub Form_AfterUpdate()
to
Public Sub Form_AfterUpdate()
(c) The syntax for the calling of the procedure is as follows:
Forms!frmYourFormName.Form_AfterUpdate
Replace frmYourFormName with your form name, and note the inclusion of the "Form_" prefix before "AfterUpdate"; this is the way Access named the event, so the Form_ must be included.
This should hopefully do the trick,
Cheers,
Steve