plugins never work!?

hello, whatever plug in I try to put into doesnt ever work. It shows up in plugin page where i activate it, and that’s all it does. I;m trying to use the adsense plug in

http://www.philhord.com/phord/adsense-inline-with-wordpress-blog-posts

and a related posts 1.3.3 plugin

none of them have worked and for the related posts, it keeps saying that it cannot load my “.php”

any suggetsions? thank you