Odd clBuildProgram function error

Did you check to see if you're creating the program object the same was as the example host? If the example openCL vector sum clBuildProgram routine works, why don't you reuse that section of the code in your host? To build the openCL program, it's pretty much the same regardless of application at least for the Altera FPGAs. As to what the problem might me, my guess currently is how you're creating the cl_program object which you're trying to build the program from. Hope this helps