Use of MD74, MD75, MD76

Hello gurus

My requirement is to make independent planning for every month, it means I wish to drop all open PIR, open PR from last month during MRP run.

Thus the open requirements will not be carry forwarded in the next month. For this I am trying to delete all old PIR from MD04.

I am trying to understand the exact prerequisites for use of MD74, MD75, MD76, I have refer a many discussions over the scn, and made relevant settings to delete old PIR, but no result is achieved.

I have set adjustment period for 30 days in SPRO and put the Key date 02.11.2015, I am supposing that PIR on 01.11.2015 and before that should have get deleted.

A same screen I am getting after MD75 and MD76, and no changes are getting in MD04.

Please help me if I am missing any step.

Regards

Akshay Naware