Trouble pulling pin Low

[mischl]

take a look where the goto command is... so it jumps only to the loop marker if your condition is true!

if portb.1 = 0 then the programms doesn't execute the lines between if and endif and jumps to the next command after endif. probaply there is nothing or only an end command. which finish the programm.

take this structure :

loop:
if portb.1 = 1 then ' only when condition is true
low portb.4
pause 200
high portb.4
endif

goto loop ' infinity

end

[crematory]

Hello

You may want to try this too:

DEFINE OSC 4 ' 4 MHz Crystal

TRISB.4 = 0
PORTB.4 = 1

WHILE 1
IF PORTB.1 == 1 THEN
PULSOUT PORTB.4, 20000 ' Generates accurate 200 ms High-Low-High pulse
ENDIF

WEND ' Infinitly repeat this loop

END