Tax defaulted in PO modifed to different Tax category however at receipt showing wrong

Hi All,

There is Tax category which is defaulted in PO based on some rules .however for the specifiec PO The Tax category should be different  we have modified the Tax catgory say from Tax category A toB.

On receipt screen and Invoice screen it still defaults the first Tax category which A not B,And user need to override again A to B at receipt and Invoice level,

Is the a Bug?

Thanks

ARUN