Hey there,

is this ubuntu server? try the following:

sudo apt-get install xinit
screen -S x
sudo xinit

leave screen with "ctrl+a", "d"

try again

also you can try CLInfo with the following command and see if your gpu is listed:
/opt/ati-stream-sdk-v2.1-lnx64/samples/opencl/bin/x86_64/CLInfo