template variables not working

I've installed 4 hacks now and none of them work. I think I've narrowed down the problem to, after I install new templates that the hacks require, and use $templatename in another template, the results from the template are not being displayed, thus a blank space, or nothing is in place of the variable instead of displaying the template. Hopefully, that made sense, sorry if it didn't. Anyway, can anyone help a poor soul?