You need to locate the Graphics settings in your BIOS and set the integrated GPU as the primary device. Save and power the system down.
Once powered down, connect your display to the on-board video connectors. With an APU+GPU Crossfire config, the APU (the integrated video) is the primary video device.
Power the system back on. Once you are at your desktop, open Catalyst and look at your hardware settings. You should see 2 video adapters. You can also play with your CF settings there as well.
Not a bad idea to ensure you have the latest drivers and Crossfire CAPs installed while you are at it.
You can get the current drivers from:http://support.amd.com/us/Pages/AMDSupportHub.aspx