Contacts are the currency of any internship. If you aren't making meaningful connections, then the internship probably isn't worth your time. You might be a natural at the job. Hell, you might be better than many of the people on staff. None of that matters if the people you are working under don't like you. The only way a prospective employer can verify your experience is through references. If you can't come away from your summer indenture with at least one person who will give you that glowing seal of approval, then you have nothing. Of course, you could be the problem. So, first try changing your behavior, and if that doesn't work, it might be time to make some money before you head back to school.
6. You Don't Gel With the Staff