Problems to load an aplication into ds5000t using mon51!!!!

Hello all!!
My name is Manu and we're from Spain. We're working on an proyect with dallas ds5000t but we've got problems. We got to load the mon51.hex that we downloaded from keil web:
ds5000_mon_9600_110592.hex. We used kit aplication to load it and it ok. The problems come when we try to load our small aplication using keil:

1) We are using a rs232 fixture of dallas.
2) We create a proyect with ds5000t as target
3) This is the code we are trying to embebe:

org 2000h
      clr p3.5
      jmp $
      end

4) We configured comunication in 9600 as in the mon51.hex requirements is.

5) What we get when we beging debbuger is always the messagge: COMUNICATION LOST.


I'll be very pleased if someone can help us because we're really surrender. Thank you very much.