i bought a crate amp and i had an older (yet decent quality) effect pedal. i was screwing with it Monday and it wouldn't work, i was just getting a LOT of fuzz through the amp.

its a crate 65 watt flexwave amp with built in effects. was it just because the pedals are compatible with the amp? or is it just my dumb fault for a faulty connection job?
probably your pedals are not compatible, all my pedals never would work on my spider amp lol, so i got ride of it...best decision of my life
Pedals can't be incompatible with amps---either ur pedal is shot, your cable is shot or your amp is shot. Most likely cable or pedal. Try using it on a different amp and see what happens--use a friend's if you dont have another one.

What pedal is it btw?
a lot of amps with digital effects or even digital amps dont really like pedals in front of them. i dont really have a better answer for why other than just because they dont like one another.

that said, it should still work. i would try your connections to make sure everything is correct before you go tossing out something.
Maybe interference from an electrical device in the same room as your guitar and amp?