Approval Purchase Order

I customizing purchase order form , below is the preview for my tab called Approval

Screenshot from 2014-12-25 16:30:33

See, there are Reason, Pelaksana and Tanggal that still empty .

when i hit Reject button, there will be a wizard showing like this :

Screenshot from 2014-12-25 16:30:53

so, in order to reject approval , you have a reason right ? so you write your reason here.

then you hit Reject button to return your reason(depend on what you write in wizard form), pelaksana(uid/user_id), tanggal(current_date),status(selection=”3″/”Rejected”) into a column in approval tab above.

but, i had an error like this

Screenshot from 2014-12-25 16:31:01

anybody know how to resolve it ?