How to enable the button buttonProformaPurchaseOrder in purchtable Form in ax 2012 ?

Hi all,

I want to enable the button PurchaseOrdreProforma in form PurchTable>>ActionPane:Purchase , if someone

know the class that manage this Class , i found  methode  DS/PurchTable/EnableJournalButtons , but i didn't found

where i have to make change to enable this button.

Thanks For Help.

Taoufiq

Thanks