Well, there are a few things you should take a look at:

MOV DPH, 0000h          ;setting data pointer
MOV DPL, 0000h          ;

Loads both DPH and DPL with the content of memory location 0. I doubt that's what you want :o)
Constants should be preceded by a '#'. The instruction

MOV DPTR, #0000h

will load the DPTR with 0.

MOV A, VAL

Again does not use the value you defined for 'VAL', but the content of the memory location 0FFh.
The same goes for:

DJNZ VAL, WR_MEM

Hope that gets you on the right track.

Best regards,
Rob Klein.