@RAMWolff The first problem that may be your issue that comes to mind, did you pregroup your figure with the correct figure groups to match the "Bones" in the rig? If you didn;t do this ahead of time in one of the grouping tool applications (or your modeler if it can do it) you probably received a "some vertices not grouped to a bone" or some such error. The groups in the conforming figure MUST match those in the figure it's conforming to.

In the video Chuck said not to use the auto grouping tool, I subscribe to this especially for content for sale. Hand grouping in a tool like UVMapper gives cleaner group lines. However if this is your first attempt to make conforming clothing go ahead and take your clothing back into the Set Up room and repeat the process but check the Auto Group box.

If this doesn't fix your problem you should at least get a chance to see the error message again and note down what it says.If this happenspost the error message and we can then try to help you again.