No VST Sound in Cubase 5

I have problems getting started.

I have installed Cubase Essential 5 and I’d like to use it mainly with VST instruments.
However, I don’t get no sound.
When I click on the keys in a MIDI key editor I hear the piano sound.
When I do the same in the key editor of my VSTi (VSCO2) there is no sound.

Under VST CONNECTIONS I have a stereo bus where the ASIO DirectX Full Duplex Driver an my onboard speakers are listed (When I use Asio4all I don’t even get the MIDI sound). I don’t know where else to look for a solution.

Can anybody help?