FPDA Altitude Callout Guage problem

I have .wav files that start at 2500ft, 1000ft, 500ft, 400ft, AproachingMinimums, Minimums, 100ft, 50ft, 40ft, 30ft, 20ft, 10ft. However, it will only call out from like, 400ft and below and sometimes as it calls out 20ft while I'm slamming onto the runway. I don't know if my altimiter has anything to do with it, but I always keep it updated where the BARO needs to be. Does anyone know how I can edit this guage so that it will call out the higher altitudes I have .wav files for, AND how I can somewhow calibrate the guage so that when it calls out 10ft, it is accurate instead of me thinking I have 20 ft but slam onto the runway?