.IPA Files not working when I try to install them on my iPod Touch

Hi all

So recently I tried installing a .IPA file from the internet. It installed on my computer fine, I clicked it, it opened in iTunes, and then I tried installing it onto my iPod 4. the blue progress bar on the PC and the iPod were going fine until it reached the end, and I was greeted with a error message saying the app failed to install.

I'm kind of a noob with this sort of stuff, so if someone could please help it would be much appreciated.