Help! Why my JR radio gliching doing FMS?

[jlagran Heli]

Hi..

I have build an JR interface for FMS, based on:

http://www.customelectronics.co.uk/fmscrktj.htm

the result is not quiet good.
I already check, recheck and recheck the interface modul, good.

Yes the TX (JR 625?) in connected to PC and to FMS (ver 6,win 98, P4).
Yes the TX can control the model,

BUT

The model sometimes suddenly move wild, even when the stick untouched!
:confused:
at CALIBRATE, the signal move accordingly to stick position, and then again
sometimes suddenly move by it self, just like glitching.

Can anyone help me? or have expereince about this?
Or error at my TX? should I buy new TX? :o

Thanks