PIR consume question

Hi gurus,

I used the strategy 11, consumption mode 2, bwd consumption period 30, fwd consumption period 30, mixed mrp 2. I create PIR in 2013.06.01, and the planing order created automatically after run MD41. GR occurs after MFBF, but the PIR is still consumed, why? The GR date is 2013.09.18 that beyond 30 days.

Regards,

Hongda