Validity period in Blanket PO

Dear All,

My Blanket PO validity start date = 01.01.2010, end date = 31.08.2010.

As of today, 14.09.2010, Im still able to post invoice. This is something strange.

I did mantained system message under OMRM with below entries, system still allow me to post invoice via MIRO.

Message class M8

Message number 297

Online message type = E

Batch message type = E

Standard message type = W (this is system auto defaut and in grey off => input disable manner)

Kindly comment what i missing or what probably that i've did wrongly.

Thanks in advance.