Cannot Connect a second monitor to HP 500-314PC

I have a new Pavillion 500-314.  It has a VGA and DVI-D connector at rear.  The comuter will not see my second monitor.  I have it conneced with a dedicated line DVI-D to DVI-D.  When I switch the monitors ,  the VGA works on both.  One monitor is old and so it is connected to VGA port.  The other monitor has both DVI-D and VGA, but I cannot get the DVI-D to work.

Any thought?  Thanks

Model No 500-324

Serial Number 3CR1900PH

Windows 8

AMD Radeon R7 grpahics

AMD A8-7600 Accelerated processor