cannot read SFR memory space (in asm)

Hello

i have this code to read int.ram and copy to ext.ram

MOV R0,#00H
MOV R1,#0FFH
MOV DPTR,#7C00H
reload: NOP
MOV A,@R0
MOVX @DPTR,A
INC R0
INC DPTR
DJNZ R1,reload

but the memory is only copied to address 0x7F.i cannot copy memory space from 0x80 to 0xFF. MOV a,@r0 does nothing in A is always 0x00 (but in debugger for example at D:0x82 i see DPL value, but i cannot get in to ACC and copy to external RAM). i have this asm code included as asm function in my C project. excuse my poor englist. please help :)