If you are positive your recovery words were written down correctly (or printed), there are a couple reasons why they may not be working. First, you may not have hit the “activate recovery” button when setting up your recovery. If you hit the “back button” during setup, we do prompt you to complete setup.
Alternatively, if you created a new recovery, it would override any old recoveries.
Lastly, if you were a beta tester, the recovery you setup for old beta accounts will not work with the production (real) app.