GSX doesn't try to control SODE jetways, it only offers you an alternative interface for SODE and, when you see that message, it means SODE told to GSX that, using the combination of your airplane doors configuration, parked as it is, no jetways could solve there.
So, the first thing to try is if they work from the SODE menu instead.
- If they don't, it clearly doesn't have anything to do with GSX, but the way those jetways are made and the place you parked.
- If they do ( work from SODE menu but not from GSX menu ), then the problem might be your GSX airplane configuration not being correct. Because the ONLY difference when calling a jetway from the SODE menu or from the GSX menu, is that when using GSX, the DOOR configuration will be the customized one coming from GSX, since it's customized for each plane. Instead, when using SODE directly, SODE will use its own database of generic airplane models.
This means using the GSX airplane configuration usually works better, because it's individually tailored for each plane, but it also means it MUST be correct, since a generic SODE config ( assuming the airplane is supported and recognized ) will surely work better than a missing/wrong GSX config.