it doesn't need the MOV R0,#base after the checks as the buffer recycles back to the start after the 6th one ,i put that in there to see if it was the problem but it didnt fix it.

I may have just noticed the problem.

Im using r0 in the delay routine before sending the reply, here

;;;;;;;
COUNTb:
;;;;;;;
MOV R0,#0FFH
DJNZ R0,$
JMP DELAYRa

If i change that to r3 hopefully it will fix the problem, it must cause the read and write pointer to be off, so the codes wont match.