Error connection imac to Wireless Lan

I have a Belkin wireless router with PC laptop connected. I’ve been trying to get my macbook pro to connect wirelessly (works fine via ethernet) but keep getting a message ‘error connection to WLAN’. have tried changing channels and triple checked I’m keying the 10bit WEP password correctly (with and without the $ at the front) but NOTHING helps..

ANy mac experts out there with clever suggestions?