Many players complaining about receiving a nonworking Titanfall beta key, Actually the codes are works but not on your platform because you received a key for the wrong platform.
If you have received an incorrect code, follow these steps:
1- Follow this link (and login)
2- Click on Email Me.
3- On the next screen, when asking for What type of Demo/Beta issue you are having, select Eligibility
4- Enter the Titanfall Beta code that is not working as the description of the problem.
5- Select Submit.
6- You will receive a new PC code within the next two hours.
If you haven’t received a code yet, you still have a chance, if you have been chosen you will receive a key no later than 11:59 PM PST on Feb 17th.