MRP Logic -Negative Available quantity in MD04

Hi Experts,

We have negative available quantity in MD04. There are no receipts generated particularly for some period even after MRP Run.

MRP Type is maintained as P1- MRP Fixing type.

Safety time is maintained as 3 days.

Planning strategy is 40.

Please suggest, what would be the reason, why i am not getting schedule lines between 09-Aug and 27-Aug which makes available quantity minus, after that there are generation of schedule lines.

Please help with inputs..