The best ideas to troubleshooting connection problems is going through this indepth article below. Most problems with mixer interaction can be attributed to incorrect/no driver installed on the Mac system.
How Do I know my StudioLive (Ai) is connected to my computer and functioning over firewire?
The above article helps assist you with two things.
1. Confirms that your firewire hardware is communicating properly and where on a PC or Mac system to view this communication.
2. Confirm that a driver is properly installed to record and communicate to your mixer.
If you are still having issues after doing the above steps, contact technical support for further assistance and they can help you get up and running.