Hi Pascal,

Whenever you create any picking (Delivery Order, Manufacturing Order), thesystem checks the availability of the stock of the product. If you have enough stock then state will be "Available", otherwise it will wait for the stock and state will be "Waiting for Materials" or "Waiting for Availability".

In some cases, you can see the stock is available yet your order is still waiting for the stock is because the stock which seems to be available is already assigned / reserved to some other process(s).

Ex:

You have 5 quantity on hand but it is already assigned or reserved to some orders. Now you are raising a MO which needs 5 or less than 5 quantity and you think you have enough quantity, but actually that quantity is already reserved and thus your MO will be in "Waiting" state.

==================================================================================================

Check Availability button checks the available (unreserved) stock and if yes it will make materials available.

Force Available doesn't check the availability of the stock and directly make your materials or products available for the process.

Hope I have explained it well and will help you to understand the flow.