airport express 802.11b doesn’t connect to Linksys E3000

airport express 802.11b doesn’t connect to Linksys E3000

Linksys support could not help with the issue = they just say the device does not support Linksys Security setting (WPA)
It was working properly with the Linksys WTR 310N v2 before and it was using WPA as well.
Even connecting the Airport Express with and wired eterneth to the router…. still does not working.

Any help?