I want to put control in migo screen.
po date is 25.11.2011
Issue date is 26.11.2011 (mb1b tcode, 351 movement type)
but gr date is 25.11.2011 (migo, 101 mtype )
at present system accepting this entry
so, I want to make a control on migo screen like gr date should be greattr than or equall to issue date.