Help with GOSUB

[HEXhacker]

Hi. First time post here. I'm using PIC Basic Pro, MPLAB ASSEM and a PIC16F870.
Need some help with the GOSUB in my code.

I'm telling a Compact Flash card that I want to read 256 sectors and then pulse
RD low 65535 times to get the 16Bit data out. I do this 4 times because the whole
file is 4 x 256 sectors.

If I put the little REPEAT...UNTIL code after each call up of 256 sectors, the program
works fine. I can push the start button as many time as I need for the whole file
to be read from the compact flash card.

If I use a GOSUB dat to go to the little dat: REPEAT...UNTIL RETURN pulse RD low routine,
the program
will only work about 4-5 times and then vapour locks. The RD pin keeps running
(pulsing low) and doesn't stop after 65535 pluses. The code doesn't recover.

Any ideas?

Thanks