Note The Cisco 3600 Access Point was introduced in Release 184.108.40.206. If your network deployment uses Cisco 3600 Access Points with Release 220.127.116.11, we highly recommend that you upgrade to Release 18.104.22.168 or a later release.
Sandeep is correct. Also, since you posted a model type of an autonomous/"s"tandalone 2600 ("S"AP2602I), vs the lightweight/"C"apwap version (CAP2602I), you may need to validate the version of code running on the AP if it does not appear to be joining.
In your screenshot, the image file ap3g2-k9w"8" indicates a lightweight version ready to join your WLC. If you find an ap3g2-k9w"7", this is the autonomous/standalone image and will not join a WLC without being converted to lightweight.
There are several threads on this process, such as this http://mrncciew.com/2012/10/20/lightweight-to-autonomous-conversion/