Cisco Wireless :: AIR-AP1220B Lightweight Conversion / WLC Support?

Is AP 1220B (b-only radio) supported for registration to WLC (7.0.x) with Lightweight software? I've managed to convert the AP to Lightweight mode, but I could not get it to register with WLC 2504 (software version 7.0). Is it possible that this AP is only supported if changing the in-built radio module?
 
In the compatibility matrix [URL] there is an information that this AP is supported on WLC up to version 7.0.x. On the other hand it is not supported by Autonomous to Lightweight Mode Upgrade Tool [URL] Since these APs does not have pre-installed MIC, it is mandatory for them to create Self-Signed Certificate (SSC). Upgrade tool could do this job (along with adding the created SSC hash to the authorized list on WLC), but it does not support this particular AP/radio. If I do the conversion manually (archive download-sw ...), the AP does not have the SSC needed for communication with WLC. I've tried making the SSC manually (instructions found on this site [URL] while AP is autonomous mode, and then converting it to Lightweight, but the AP still could not register to WLC.

In the debugs (on WLC/AP), I am receiving an error that is described in some Cisco troubleshooting documents as something related to WLC not having an SSC hash in the auth list. Problem is that the AP is not even sending standard CAPWAP messages and there is nothing to be seen in "debug pm pki enable" on WLC...