Thanks for your answer Mike.
The example you give me works fine:
oUser = GETOBJECT("WinNT://serverh/hlizarraga,User")

but why not this others:
oUser = GETOBJECT("WinNT://Informatica/Rhdinf14/hlizarraga,User")
oComputer = GETOBJECT("WinNT://Rhdinf14,Computer")