It's not possible!
You can't believe where was the problem!
It was a hardware problem!!:
I'm using a rs485 net, and there was a short-circuit on the Tx-enable pin of my rs485 converter..
so the char I was reading was noised by strange trasmissions on the line!!! the char I were sending was right, but the received one was mixed with other stranges things..

sorry. The program was working right.
Thank you Bruce for your attention.
C yA
Simone.