3Com/HP A8760 - Repeater mode

[Mathia]

Hello guys, I need your help!!
I configured two access points in repeater mode to extend the range of my wireless network.
An access point is configured as the Root Bridge, the second as repeater.
The SSID and encryption are equal (Tkip, WPA & WPA2 with same pre-shared key).
The two access-point connect to each other properly. In fact, removing the wired connection from the repeater can still pinging. In "stations status" authentication, association and forwarding allowed are "true".
The problem is that I can not authenticate any PC to the wireless lan. In fact when I try always receive a generic error where it says "can not connect to the network ...".
If I configure the same access point as a normal AP clients can authenticate regularly to both.
I'm losing my head.... :( what's the problem? Does anyone have a solution to ensure that the repeater function works correctly?
thanks!