planned orders not generating

Hi,

I have one issue in MRP that

we are running MRP using MD50 ,sale order-244. While running MRP for my material the planned orders are not generating. I have analysed the issue and find the possible reasons that already for this rework order is created. i am not understanding that without parent order how rework order is created. Because of this only planned orders are not generating. For this i have given solution to the user as delete the rework order and try the MRP. Is this is the correct way or not. please guide me the possible reasons.

Regards,

Mastan.