Upper Thread Error

Question

I am trying to embroider on my Brother Innovis 4000D and I keep getting an error "Check and rethread the upper thread." I have rethreaded changed the bobbin (and bobbin case) changed hoops and stabilizer and replaced the needle. I still get this message and the few stitches it does manage to embroider in between messages, are a mess on the back side. The upper thread is making very loose loops on the bottom side of the design. Any suggestions?