USC Letter of Req

It is okay to have just one teacher recommendation and no counselor recommendation? I had my counselor send my transcript and school report, but she opted out of writing a letter of req. Is that okay for USC?

Most (if not all) Common App schools (USC included) require a counselor letter of recommendation. Why would your counselor not want to write you one? USC allows up to three teacher letters of rec, but they are all optional