Note : Linux OpenCL runtime is integrated with the Catalyst Linux driver 12.10 or later.
May be you are having some problem in installation or setting environment varial as you mentioned...
Please go through the below link and check have followed the same steps.
I did not think about reinstalling everything. But it seems to have worked.
Although now does the BoxFilter Sample complain about the GL/glu.h missing.
But I guess, that I can figure that our by myself.