The 1142 series LAPs are supported only with WLC release 5.2 and later. If you run WLC versions earlier than 5.2, you cannot register the LAP to the Controller and you will see an error message similar to this:
*Mar 27 15:04:38.596: %LWAPP-5-CHANGED: CAPWAP changed state to DISCOVERY
*Mar 27 15:04:38.597: %CAPWAP-5-CHANGED: CAPWAP changed state to DISCOVERY
*Mar 27 15:04:38.606: %LWAPP-3-CLIENTERRORLOG: not receive read response(3)
*Mar 27 15:04:38.609: lwapp_image_proc: unable to open tar file
Mar 12 15:47:27.237 spam_lrad.c:8317 LWAPP-3-IMAGE_DOWNLOAD_ERR3:
Refusing image download request from AP 0X:2X:D0:FG:a7:XX - unable to open
image file /bsn/ap//c1140
In order to register the 1140 LAPs to the WLC, upgrade the firmware on the WLC to 5.2 or later versions.
Problem 16: 1000 series LAPs not able to join the Wireless LAN controller, WLC runs version 5.0
This is because WLC software release 184.108.40.206 or later is not compatible with Cisco Aironet 1000 series APs. If you have a Cisco 1000 series LAP in a network, which runs WLC versions 220.127.116.11, the 1000 series LAP does not join the controller and you see this trap message on the WLC.
"AP with MAC xx:xx:xx:xx:xx:xx is unkown"