Customers reference from quote to order in sbo 2004

Hi

I am trying hook onto the choose button when you create a sales order from a quotation, so I can bring through the customers reference from the quotation.

If I use the code pval.before_action = true, when I update the reference field the wizard doesn't finish. If I use the pval.before_action = false it never runs !

Can anyone give me any ideas please ?

Regards Andy