Connecting IMAC to PS3 wireless airport, PS3 ip timed out

Ok I have spent a few hours at it yesterday and finally my PS3 can recognise the wireless airport network I created on my IMAC. However, when the PS3 goes into the final step to test the connection, it states that the ip address has failed and timed out. Any suggestions? I tried entering the ip address both manually and automatically.

I would purchase a cheap wireless router and use that instead. Game consoles are notoriously fickle about wireless connections, and using your iMac as a WAP is more trouble than it's worth.