Could anyone please tell me why there is nothing displayed on my display screen?

I am doing an image processing project based on FPGA. The first work I need to do is flipping the image horizontally. I think there is no problems in my program (the program is attached). There are also the screenshots of Platform Designer design and Programmer design. I think these are OK but after uploading the program into FPGA which is connected with the display screen, it suggests the uploading is successful but nothing displayed on the screen. I am not sure where I make mistakes. Maybe because I forget some important steps? Could anyone help me check where the problem is? Thanks a lot.