If you're trying to fly the cargo containers then you're seeing that because cargo containers can't move at all.
If you've got cargo containers in your squadron, ie. You're flying in a ship and added cargo containers to your squadron in the hopes of just having them tag along, then you might get that message as well. If you're flying in a squadron, all of the ships have to have at least some sublight speed, and if you want to hyper, they'd have to have some hyper capability as well. Cargo containers have neither, unfortunately.