Kitchen plumbing clogged up.?

My kitchen sink is clogged up. It has happened before. Usually I run an electric snake from behind kitchen sink which is in the garage. I put it in through cast iron pipe that goes straight down into ground. Usually it does unclog, but this time it doesnt want to. Is there any suggestions as to what to do. I'm usually do everything myself, I am trying to avoid getting a plumber. I just want more suggestions, before I give up and have to hire professional.