Take off

Hi, just got myself a PCM rx. Put a brand new chrystel in it and tried to set it up. Have two other PCM rx the same and PPM so no a bit about them set up wise, but somthing seems very wrong with this one. When The PCM rx is set up the servo's dont move smothly as they should, they sort of bounce. There is no clitching or anything like that just iratic movments when the servo's are asked to move. Does this sound like a dodgy rx or am i missing somthing.

Thanks

Paul