It may be, for a variety of reasons, that the internship is not acceptable to the department for credit. This has no easy answer. If you've invested four years getting your degree, you're entitled to expect more than an entry-level job flipping burgers. Set your sights on the kind of work you can imagine yourself doing as a job after graduation. First, remember that you must have completed 12 credits in your major before you're eligible to take an internship for credit.
Most students do their internships in their junior or senior years.
Your junior year is a particularly good time to meet this requirement, because it leaves you time to do another internship. If your experience confirms your interest in the career area you've examined, it's helpful to get another internship in this area. On the other hand, if you decide you don't like the area to which you're introduced in your first internship, you have time to complete an internship in another career area. I'm working part time at an organization right now and my job sounds like something that would qualify for an internship. Maybe, but it's unlikely.