timing constraint on DE2-115

Hi group,

I am using DE2-115 and one D5M camera to build a small imaging system. I used the demo code from D5M CD and the system worked perfect. Then I extended the HSMC port on DE2-115 to 3 GPIO ports using H2G board from Terasic. I also changed the pin configuration of the design. Now I can still see the image from the camera, but it is shifting very slowly, where more and more right side of image shows up on the left side.

I am wondering if this is a timing constraint issue, because I only changed the pin configuration. And if so, what is a good starting point? Thanks very much!