Altera PL-APU USB Master Programming Unit (Power supply ratings Help!)

I attached a 5Volt DC power supply with a 1amp current rating. I figured chances are it would not be a lower voltage rating than 5 Volts so I took a chance. Well the Adapters programming light was vary Dim so I moved it up to a 6 Volt DC and still it was quite Dim, so I then used a 7.5 Volt DC supply and it seems to be at the regular brightness as the PL-ASAP2 programmer. However the Software is failing to detect the installed adapters.