As I recall, your original Q500 was one of the few that came from the factory with an ST12 instead of an ST10+. I assume you are trying to bind the new Q500 to your original ST12?
If you are trying to use the ST12 that came with your first Q500, you will have to create a new "Model" on the ST12 first, and then run through the bind process to bind it to the Q500. It will not work if it is still selected to the model for your old Q500.
If you are having an issue with the ST10+ that came with the new Q500, please let us know, and we can work through that.