Hi Tendayi..
If you are using the PLD then Try this
- Create one database field, map the Table - OINV and Column->draftkey (for example this field's Unique ID F_200)
- Create one formula field , F_200 == -1 (for example this field's Unique ID F_201)
- Now link this F_201 to document total and document number and some important fields.
- Now if some one try to take print before add, system wont show those linked field. So printout is not valid.
- After add system will show all the values.
Hope Helpful
Regards
Kennedy