Okay, I'm just curious. The last time I shopped at DL, the cast member told me that I needed an ID. I'm 16 and I have annual pass. When you go, do you have to show ID?
They are pretty strict about the I.D. thing for AP discounts now that they have removed the photo from the AP card. I have been told by various CMs that a school I.D. is accepted for minors. My sons are still in elementary school though, and their school doesn't issue I.D.s, so they have had a couple problems when making purchases since they got their photo-less APs.
If you have a picture ID from your school, bring that, it shouldn't be a problem. If the cast member won't accept it, ask them to call their lead and double check. Sometimes they just get confused, or don't realize that someone is under 18.