strategy 70 no PIR consumption

Hello..!!

For FERT I am maintaining SG 20 and to plan HALB I am using SG 70 .As per rule the production order of FERT should consume the PIR of HALB.But the consumption of PIR is not taking place.I am using mixed mrp,consumption mode and period at HALB level.Tried all possible things but no consumption.System is just creating planned orders without consuming PIRs.Please help.

Regards

BDS