Automatic uload from GTC to GC not happening

edit: automatic upload, that is.

I did a search and browsed but I could not find an answer so here goes.

I have been using a FR 405cx since last year with no problem. Last time I updated GTC, it stopped uploading activities to GC automatically so I had to go into GC and upload from there. Somehow I fixed it but I can't remember how. I bought a 310xt and not it's doing the same thing. It uploads fine to GTC but then I have to go into GC and upload from GTC from there. It's an extra step and I know there is a way to fix it but again, I can't remember how. Does anyone know how?

If it matters, both devices, the 405cx and the 310xt, are still associated with my user name.