error

Traceback (most recent call last):
  File "main.py", line 44, in <module>
    example.execute()
  File "main.py", line 32, in execute
    self.program.part1(self.queue, self.a.shape, None, self.a_buf, x, self.dest_buf)
  File "/usr/lib/python2.7/dist-packages/pyopencl/__init__.py", line 457, in kernel_call
    self.set_args(*args)
  File "/usr/lib/python2.7/dist-packages/pyopencl/__init__.py", line 509, in kernel_set_args
    % (i+1, str(e), advice))
pyopencl.LogicError: when processing argument #2 (1-based): Kernel.set_arg failed: invalid value - invalid kernel argument