PR should be Firm

Hi

Our client requirement, they will take MRP run every day. After MRP run they want firm PR.

For this I am using MRP type P1 & Planning time fence I have given 1 Day.

There is no Planned Deliv. Time.

Suppose that today I got requirement for X material & taking MRP run today itself.

System is generating PR but it is not Firming.

What are the possible reason.

Regards

ARK