Pick release error - Line back ordered when sufficient qty exists

Hi

I am trying to pick release a line but the line is going to back ordered and showing exceptions. When i check Availability there is sufficient On Hand Available Quantity and  Reservable quantity. (See screens attached). While executing the Pick release, "Pick selection list generation" request is going to "Warning" status after completion.

Why am i getting exceptions and not able to proceed fro pick release to confirm ship even when On hand quantity is available

Thanks

Abhi