My mailed in return was rejected for a missing sch A and wanting line 8 supporting info which is standard deduction. I'm 17 and has one W2 and I am confused?

[Carl]

If you were 17 on Dec 31 of the tax year then most likely you did not check the box for "I can be claimed as a dependent on someone else's return". My bet is, you qualify to be claimed as a dependent on your parent's tax return, and you did not check the aforementioned box on your tax return.
Understand that it does not matter if your parent's actually claimed you as a dependent or not. If your parents "qualify" to claim you, then you must select the option for "I can be claimed as a dependent on someone else's return". You don't have a choice in that, unless you can prove to the IRS that you provided more than 50% of your own support for the entire tax year.

So did you check the box to indicate that someone else can claim you as a dependent?

Is the amount shown on line 8, $12,000? If not, then what amount is shown there?