Component Pick Release Error

While performing component pick release the following error is obtained: 'None of the material requirements for the selected components could be allocated. Please re-query to view the open requirements'

There is 1 component - for which the supply subinventory does not have any stock.

Also the following check were performed:

1) Supply Sub inventory is not reservable.

2 ) Source sub inventory is reservable.

3) The component used is lot controlled. But we set partial allocation allowed in pick rule.

4) Inventory Picking rule is also defined in Organization parameter.

What can be the reason for this error message?