Currently Being ModeratedOct 11, 2012 6:37 PM (in response to kiwi135)
For a wireless printer to appear in the Default view when you select to Add a printer, it must support a protocol like Bonjour. I would assume a Brother wireless printer does support Bonjour so another cause for it not showing is that it is using a different IP address range to what the iMac is using.
To check the IP address ranges being used, on the iMac you can open System Preferences > Network, select the wifi entry in the left pane. The right pane will show what IP address the Mac is using. If you then press the Advanced button and then the TCP/IP tab, this will also give you the Subnet Mask and Router address.
With this information you should then check if the Brother is also using the same Subnet Mask and Router address. There should be an option to print or view the network address settings currently set in the Brother.