FDA: how to populate the Serial Number based on last serial number

Hi,

I have an app with (Find/browse) form , this will list the data when clicked on FIND, one of the grid columns is the Serial number(grid row number). Now when i click on ADD button in the FIND/BROWSE form, it will call the FIX/INSPECT form and in this new form i want my serial number to be auto populated based on the serial Number in the last grid row of previous find browse form.

I tried getting the BC value and assign it to a variable in the event "last grid row fetched" and then in the ADD button ER, i passed this variable as form interconnect to the fix/inspect form. And in fix/inspect form i used the FI value and incremented it by 1 and assigned it to the BC Value, but this did not work.