Serial tx/rx doesn't work

Hello everyone!

I am having the following issue. I have two xbees and I am trying to create a communication between a mbed and the PC.

I have one xbee USB explorer with one xbee to the computer and in the other side, a xbee connected to the mbed with the serial tx/rx pins to rx/tx xbee pins.

Both xbee have same configuration (no coordinators, just a serial wireless communication). The problem is that with one xbee connected to mbed the systems works, but when I switch them, the system stops to work.

I have been testing a lot of differents configuration and my conclusion is that one of xbees can’t do the serial communication to the mbed by pins.

Any possible solution?
Thanks for your answers.

which Xbee product are you working with?

What voltage level is your mbed and what level are the data lines?