If you're having issues with linking your YouTube account there could be multiple reasons.

First step is to ensure that the account that you've linked has a channel setup. If it doesn't, please set it up here:
https://www.youtube.com/create_channel

If that doesn't work, then please try logging out of all of your Google Acccounts. This can be done on the following page: https://accounts.google.com/ServiceLogin

Once you have logged out of all of your accounts, please try and link your selected account again.

If you're still experiencing issues this time you should try creating a completely new YouTube account. Once your account is created you should setup a channel on your YouTube account through the following link: https://www.youtube.com/create_channel

Once done, you should be able to link your account without any issues.