[RTTY] KENWOOD TS2000 AND FSK

[Kostas SV1DPI]

I build a simple interface for a friend's ts2000 (to connect the soundcard,
ptt, cw, fsk).
My interface is simple with a resitor and an optocoupler 4N37.
I made the connections to acc-2 and cw as the manual of Kenwood ts2000 says. 
Ptt, cw and data in/out work like a charm. But the fsk doesn't play (i 
listen a steady tone
in monitor, not diddles). I checked and the com port is ok
4n37 seems to work as i have a led in serious and lights with the right 
rythm
Any menu to look for as my friend doesn't know the radio quite good, or any
other things to check?
Ofcourse he can work afsk until we find a solution
Tnx for the help in advance
Kostas sv1dpi