When are PR's generated in md04?

Hi All,

Im running md04 for a material whose

Re-order point - 150

Max stock level - 200

Safety stock - 50

Lot size - hb (replenish to max stock level)

MRP type- VB

When i ran it for the 1st time , i got available quantity as 150 units and reqmt/receipt - 200 for the 1st PR. Next i added some stock through 561 mvt type and the available quantity changed to 200 units. Then i created a reservation for 100 units, 1 week after the 1st PR fulfilment.

Now question is after creating a reservation why isnt mrp triggering pr for 100 quanity as available quantity fell to 100 and it should replensih to max stock level which is 200 ?