DHCP option 43 would be enabled on the DHCP server. It is used to tell the APs the IP address of the WLC. Leo asked about it because the message you put there is referring to this. It only means that it could not discover the WLC's IP address through DHCP.
How do you expect the AP to know the IP address of the WLC? You said you set this up manually on the AP right? Did you use the command "capwap ap primary-base <wlc name> <wlc ip address>"? This command would tell the AP the name and IP address of the WLC but it is important that the name matches what is configured on the WLC.
As for the image, don't worry about this now. The WLC houses all the AP images. Once the AP joins the WLC it will see that the image it has doesn't match what the WLC has and it will pull the correct image from the WLC.
To find out why the AP is not joining you should debug capwap on the AP with the debugs listed below and pull the join statistics from the WLC.
From the AP:
debug capwap client event
debug capwap client error
!!Let these run for 5 minutes and make sure to log the output to a text file!!
"undebug all" to stop the debugs
On the WLC CLI:
show ap join stats detailed <AP mac address>
!! If you are unsure about the AP's mac address use the command below to find it based on the ip address!!
show ap join stats summary all
