I got this trap massage on WLC.
The client failed to communicate, it was still associated wiht WLC though.
the trap massage log is blow
"Decrypt errors occurred for client 00:40:96:ae:38:fe using unknown key on 802.11a interface of AP 00:16:9c:b8:9b:5"
My wirelss environmet is containing WLC2106(5.2) 1131AG, clinet using ADU(v4.4)