Make sure that you've completed all three sections (Your Driving Attitude, Signs and Rules and Sharing the Road with Others) and that you have earned the key for each section. You need to successfully complete the Challenge for each section to earn the key.
Alternatively, If you attempted the Learner Test and did not pass, you will be locked out for 24 hours. The time and date you can access the test is displayed at the bottom of the home page.
Alternatively, If you attempted the Learner Test and did not pass, you will be locked out for 24 hours. The time and date you can access the test is displayed at the bottom of the home page.