Ok, I found a solution but i don't know what is the problem.
I'm using these modules with a PARALLAX 32400 rev C to connect XBEEs with my computer.
I retried the same test with the computer of my colleague and the new module is able to communicate with my old XBEE end node.
I tried this test also with another computer and the communication doesn't work as on my computer.
I reached a stable and functional test only if I plug the PARALLAX to an USB Hub. With it the new module is able to communicate both from my PC and from the other that doesn't worked.
As introduced before, I don't know why!
If some of you found the same problem, please comment this.