OK, we've got something to work on now...

The problem you're having is that you've set A.0 for Output, and then performing a Read (Input) operation on it... sometimes this doesn't work and sometimes you can get away with it... to be bullet-proof try this...

LEDStatus var bit ' Add this variable

RECEIVE: IF PORTB.2=0 THEN
SERIN2 PORTB.0,8380,RECEIVE,[WAIT("TUV"),REC]
HIGH PORTA.0:LEDStatus=1
ENDIF

REPLY:
IF LEDStatus=1 THEN
IF PORTA.1 = 0 THEN
SEROUT2 PORTB.1,8380,["TUV",PRESS]
LOW PORTA.0:LEDStatus=0
ENDIF
ENDIF

If it still doesn't work then you must ask yourself...

Is PORTA.1 Low?
Have I remembered that A.1 needs a pull-up Resistor?

Melanie