OpenCL application Hangs

Hi,

I have an OpenCL multithreaded application that is targetted to a GPU.

I am trying to target this application to the Altera FPGA.

I could successfully build the host executable and the offline aocx file for the application.

Upon Execution, I encounter a hang.

I traced out the place of hang to be before the call to clFlush

What could be the cause for the hang?

Does Altera support Multithreading ?

Or Is clFlush functionality incorporated in Altera's OpenCL Implementation ?

Thanks