I was developing a kernel for a while on my machine (R9 270X, Catalyst 14.12) and everything run smoothly. But then I got to execute it on another machine (HD 6520G), just to get the following error: clEnqueueNDRangeKernel (CL_INVALID_WORK_GROUP_SIZE).
These were the workspaces I was using: global (52, 4096), local (16, 16). So, the problem was that global was not a multiple of local.
The question now is, why was I able to run the kernel on my machine? Is this a feature, or a bug?