midi keyboard not producing sound

I’ve reinstalled Cubase 7 a few times over the last few days. I was having problems getting my VST Instruments to work. Now that I have it working again, when I try using my midi keyboard, the blue lines go up showing it’s responsive but it isn’t producing sound. In the devices menu it recognizes that it’s there just that it’s inactive.
What can I do?

Thanks ahead of time

If I understand it, the blue line of Transport panel (right?) are going up and down. So MIDI data goes to the Cubase. Or do you mean the blue line of MIDI track?

Maybye stupid question, but… Is you Record enable button switched On (is it red)?

What type of MIDI Input do you use (All MIDI Inputs, or specific port…)?

What about your system? Are you using Windows, or Mac OS X? 32-/64-bit?