Can't connect to wifi expander

[kei84]

Hey, people.
As I was getting a weak signal in my room, I decided to buy the linksys WRE-54G wifi range expander. The router I have is the linksys WRG-54G.

Router signal in my room: 23%
Expander signal in my room: 100%

I can connect to the expander signal using my iMac and PSP Go (Playstation Portable Go) just fine, but for some reason I can't only stay connected using my notebook (running LMDE gnome) for a couple of minutes. After that it connects to the router signal instead of the expander signal.

Does anybody know how I can solve this problem?