I'm assuming you have the correct driver for the OS X version that's installed?
I don't know anything about that piece of hardware, but the release notes for one of the drivers I looked at has something about the Tascam Control Panel app. Does that software see the hardware, and report the driver and firmware? If it does, what about OS X's Audio MIDI Setup application?
This link is for Focusrite, but it probably would be something to try. Doesn't seem like it can hurt anything since it will cause the preferences files to be regenerated.Thanks, I reads the control panel, but nothing else, wont show up anywhere on the mac??