FPGA Image subtraction

Hi,

I need to subtract 1 image from another to do some background removal on a FPGA target (myRIO-1900).

I'm using the "imaq FPGA Subtract VI" to do the operation and I'm transfering the images from the host to the target using DMA FIFO.

I'm not able to extract the resulting image from the output FIFO and the code is stuck on the "Imaq FPGA Image transfer from target VI".

I can't seem to find the cause of the problem. I tried to test each "output/input valid" and "output/input ready" on the FPGA VI bus and they seems to work just fine.

I also tried to put a "time out" on the "Imaq FPGA Image transfer from target VI" but the output image I got was not correct.

I have attached the images I'm using and the screen shots of the VIs (FPGA and RT).

Thanks.