My customer is encountered a problem of Availability Check. Some of the material they need to release the Prod order are not in stock (we have 0 in actual stock - MD04) but SAP says that "All materials are available". I checked the master data for this items and there is no difference with the other good ones. they all have the same availability check configuration. I noticed however that they posted inventory differences (mvt 711) with WM each month. Maybe the availability check of SAP is based on the inventory levels posted in the WMS.