Paid to have access to the teacher deduction. I received it. Yet my tax liability remained the same, before the credit and after. Shouldn't the deduction have lowered it?

It depends.  The deduction for "Educator Expenses" is not a credit.  A deduction reduces taxable income whereas a credit reduces tax liability dollar for dollar.  So, if your taxable income is already zero that will not change when adding more deductions.  

To see what may be happening with the deduction you can "Preview Your 1040" using the steps below in online products or view your form 1040 in "Forms Mode" in desktop products.  Look at form 1040 lines 10-16 with the deduction included and not included to see the changes. 

1. Select "Tax Tools" in the left hand menu
2. Select "Tools"
3. Select "View Tax Summary"
4. Select "Preview My 1040" in the left hand menu