Mitsubisi WS-55613 Computer monitor connection

I can not get my Mitsubishi 55613 to recoginize my computer.  My computer recognizes the TV as a monitor but the TV is not recoginizing the computer.  I have added COMPUTER in the device setup menu, and I am using the VGA monitor connection.  I perform a FUNCTION F7 on my computer and it changes to the correct screen, however the TV does not change.  Any advice?