Error when i confirm purchase in enterprise portal

Hi!

I was asked to add the option "Confirm Purchase" available in PurchTableListPage to Enterprise Portal (AX2012 R2).

All i did was to grab the "ButtonConfirm" from the PurchTableListPage  form, and set the property DisplayTarget to Auto. 

Now i see the button throught EP, and it correctly enables and disables as it should, but when i press it, i get an error with empty message.

Any clues??

Thanks!

Jorge