Both the same error effectively.
You have no results in your query, so therefore you cannot move to the first record. Use mysql_num_rows first to verify you have records in the resource.
Hopefully you're not making a habit of using mysql_result. Its slow, and if you were to run both of these blocks in the same script then you query twice for information that isn't required. Query once for any information you need and use PHP to lookup what it needs from the resultset or a stored result. It's fine if you only call one and only need one at a time though, but since you can be limited in querycount per hour, you should be doing whatever you can to reduce the number of queries required.