Multiple Joint Roots Found error message

I posted this under the Q&A section a couple of days ago also. I'm trying to upload a model from CC3. First I set the model into a T-pose, then export from CC3 as an FBX file. I open the FBX in 3DXchange and then re-export it as an FBX but without the animation. When I upload it to Deepmotion, I get an error message about the model having multiple joint roots.

Am I doing something wrong? I'm using the free service if that makes a difference. I tried to upload the model, but I get an error on every upload with a "code 0" response.