validation period in condition type

Hi all,

Condition type JVCS ( CST ) , maintained in the trx code FV11 4% on date 01.04.2006 to 28.03.2007 .Earlier

it was 3%.

They have created the P.O on 28.03.2007 ( last validate date ).In P.O it is fine 4 %

They have done G.R on 29.03.2007.While G.R system picking 3%.

Client asking, G.R created based on P.O ,why system picking 3%

Regards,

rv