What version of Premiere Elements are you using and on what computer operating system is it running?
To verify that your YouTube account is useable, have you exported your Timeline content to a file saved to the computer hard drive
and then uploaded that file sucessfully from there to YouTube at the YouTube web site using the same account?
Another thought is to go to the YouTube web site and make sure that you are signed into your account there. Leave YouTube opened and you signed in there.
Then open Premiere Elements and try to upload the Timeline content to YouTube using the Premiere Elements YouTube feature using the same account number.
Is your Internet connection working?
We will be watching for your results.