Hi Imran,
The PIRs in your case are not considered for availability check and they are displayed only for information purpose. There could be many reasons for this, the most common one is "period of adjustment".
If you have maintained period of adjustment then all PIRs that fall under this period will not be considered. You can find this value in customizing transaction OMPG. Check for your plant and MRP group assigned to this material.
Now, since PIRs are not considered, system finds one process order of 156175 Qty in next month and issues an information message as exception 10 - Reschedule in. This process order is covering your present requirement.
This could be the reason for planned orders not getting generated in your case. Try removing MRP group from MRP 1 view and enter new values of PIRs. You should get availability qry for new PIRs. or change the values in OMPG.
Regards,
Rohit