Penalised for late tax return even though I wasn't working in that time

Hi, so today I got a letter through the post indicating that I have been charged a penalty for a late tax return. The issue is I wasn't even employed or self employed in that quoted tax year: I was still in full time education. I really don't get why I have been penalised. The frustrating thing is when I try to appeal it states I need to file a tax return for the quoted year. When I try to file one it literally states "there is no history of employment so you don't need to file a return." I'm just going around in circles at this point.

Hi Bladesmanstan,
If you do not meet the criteria for Self Assessment for the tax year that you have received the penalty for then we can review if the tax return can be cancelled. To review this you will need to contact HMRC: Self Assessment: general enquiries.
Thank you.