I just fixed a similar issue with a 1242 yesterday as well as having run into it in the past. There is a known issue with AP 1200s when using PoE from a switch. I would have to do some digging to find the documentation, but the AP will power up and the radio interface will be shut down. If you web into it, you will see an error log regarding in-line power negotiation. You will then be directed to the System Configuration page under System Software. Change the setting to Pre-standard Compatibility and is should work fine.
Hope this works for you.