Please help - Endless loop

Hi Guys,

I must have an endless loop in this program, as LCNC hangs as soon as I load it. 
I have been through it twice, and can't see my error.

The first loop starts at X-4, and loops as it increments up in 8mm steps across to X52, while the second loop starts at Z30, and increments down in 6mm steps, until reaching Z0.

Without LCNC calling the error, may I please request you check this and let me know what I have screwed up, as I can't see it?
Thanks.
Mark
 

#1 to #30 are used to send variables to a called subroutine, so them are not writeable in the sub. If names given from #31 up, it should work

Thanks a lot. 
Cheers,
Mark