Hi.
There can be many reasons why your warehouse shipment lines cannot be shipped.
Assuming that you don't have Require Pick enabled and that, as Kim correctly suggested, you have Qty to ship populated in the warehouse shipment line, I would check the following:
- Check that Item Tracking is not enabled for the item you want to ship. If yes, you need to add either a Lot number or a Serial number in the item tracking line before you can post
- Ensure you have enough availability to ship the item.
- If you use Bins, check that the shipment Bin on the warehouse shipment header is set up as a shipment bin and that you have availability in the bin on the warehouse shipment line.