Basic RTX51 code

Hi!!

I have a basic code under RTX51, read/write serial port.
Without RTX51 control it work ok. But if i use RTX and download my project to the target it dont work.

I have saw the example code TRAFFIC, and i include all different files:
RTXCONF, RTXsetup, STARTUP. I modificated anyfiles to put xdata, and to select my micro but i dont know why dont work.
Im looking similar examples but i cant find the solution...

My micro is AT89C51ED2.
Any idea??

Thanks