title: Opencl clGetPlatformIDs error -1001
body: <p>I am trying to run some OpenCL programs. 
  I have a NVidia graphics card (GeForce 6600). </p>
  
  <p>But , when I execute my program and I get a error : 
   Unable to get platforms -1001 </p>
  
  <p>My OS is ArchLinux and I already install the following packages (
  from pacman ):
  1. libcl
  2. opencl-headers
  3. opencl-nvidia-304xx
  4. lib32-opencl-nvidia-304xx</p>
  
  <p>How to fix this problem in my environment？
  or what necessary packages need to install?</p>
  
  <p>thanks. </p>