problem with printf extention

I wrote a opencl program on kaveri (A10-7850K).

But I want to printf the messages in kernel when I used the type "cl_device_type_gpu" .

I added the "#pragma OPENCL EXTENSION cl_amd_printf  : enable" in kernel code .

It will fail to execute the program.

But when I used cl_device_type_cpu , it worked !!!!

clinfo shows that it could use cl_amd_printf .

The driver version is opencl 2.0 driver and sdk version is 3.0.

Thanks