The VGA adapter switches tell your Mac what resolution the monitor is, but they don't tell the monitor anything. Many modern monitors use a communications scheme, the name of which I have forgotten, to interrogate the host to find out what resolution and speed they're running at.
I would guess it's that latter thing screwing things up. I would check the LCD panel owner's manual to see if there are any settings that let you bypass that feature. A long shot, but...
The above is assuming you don't have a failed cable or adapter.
I also remember something about using a Radeon 7000 with an LCD panel and getting a blank screen, but my mind can't lay its hands on the details. That was about ten years ago, and I think there was some kind of workaround, but I just can't remember. You're not using a 7000 of course, but there might have been relevant info in that problem set.
It sounds like you have the Apple version of the Twin Turbo card. The ixMicro version had two video connectors. You might try installing the extension for it.
http://www.prismnet.com/~trag/9600_Graphics.sea.hqx
The only reason 9600 is in the name is because that card shipped in the 9600.
I would guess it's that latter thing screwing things up. I would check the LCD panel owner's manual to see if there are any settings that let you bypass that feature. A long shot, but...
The above is assuming you don't have a failed cable or adapter.
I also remember something about using a Radeon 7000 with an LCD panel and getting a blank screen, but my mind can't lay its hands on the details. That was about ten years ago, and I think there was some kind of workaround, but I just can't remember. You're not using a 7000 of course, but there might have been relevant info in that problem set.
It sounds like you have the Apple version of the Twin Turbo card. The ixMicro version had two video connectors. You might try installing the extension for it.
http://www.prismnet.com/~trag/9600_Graphics.sea.hqx
The only reason 9600 is in the name is because that card shipped in the 9600.