SNP PReq creation

Hi Experts,

I need your help in understanding the system-behavior for creation of SNP PReqs. We are using SNP heuristic as planning engine.

I have two questions here :

1. Why system does not create one PReq each for each Forecast demand when the lot-sizing policy is lot-for-lot ?

2. For the Forecast of 11th Jan -- the available stock is going in negative.Why does system not procure in-time to avoid going in negative ?

Please help.