Links on Facebook Show Different Thumbnails to Another Site

[hyperviperx99]

Hi there, every time I post certain links of a forum section on Facebook, such as the link shown below, it links to a different site. (a marketing site) Have I been hacked? Is there a bug? Please let me know how I can fix this problem.

http://www.fliprap.com/forumdisplay.php?88-General-Forums