Thanks for advice! Actually i do not need dual dptr-s for speed, it just seemed to be a nice alternative to stack operations(i do use dual dptr-s in other places of my code and it seems to work ok). After modifying code to push/pop everything works perfectly. I am just a little bit curious- what the heck, if there are 2 dptr's, i should be able to use them as i wish!? Probably i misunderstand some important part of Rules or syntax or smth...
In my code the write_spi_byte adresses dph & dpl "separately", not dptr. Could this be a problem? Another possible source of trouble might be Metalink's old assembler. I modified it's *.mod file but may-be incorrectly?
I disabled all int's before entering this sub and i THINK (should double-check it!) there are no other bugs and DPTR0 is selected by default.
Could you point me out the difference between "setb" operation at WMCON and direct XRL (toggling the DPS bit). It SHOULD result in same result?

Thanks for Your patience!