Master scheduling not exploding to lower levels

Hi,

When running Master scheduling it is not exploding to the lower levels.  We have inventory on many items but the MS result shows Planned purchase orders for all items even those with on-hand inventory.  If I run Master scheduling on the individual items and then re-run for the Parent item it explodes correctly. 

Question: why is it not exploding down through all levels?  Is there a setting that needs to be turned on?  Any suggestions are greatly appreciated.

Thanks.