I am not with Laminar Research; just a flight simmer.
When you purchased the pedals did you receive installation software? If so, have you installed that software? If so have you attempted to callibrate the pedals within X-plane as well?
If you were using Logitec (ex Saitek) pedals my advice would be to "totally" delete the saitek software and reinstall and calibrate the pedals only through X-Plane. This is the only way the saitek pedals will work in a satisfactory manner.
Try this same process with the pedals you have acquired. It may work.