After you file

Ok maybe I didn't I do have question ? About the end of April or May I filled my tax thing bye mail. I put zero on the whole paper and after waiting a few months I called the IRS myself and the person I spoke with told me on line 30 I put down zero. Ok but it was supposed to be for the 1800 for the two stimulus checks.. I didn't know that I got confused and that they where asking about tax money owed to me . The man told me to refile again and put 1800 on line 30 and I would get it. He said to file E file it was a lot faster. What i don't get why is my tax thing rejected. Why