What version of Premiere Elements and on what computer operating system is it running?
What is the file size and duration of the upload according to the YouTube upload area within Premiere Elements?
What are the properties of the Timeline that you are trying to upload to YouTube? Have you tried a different Timeline content for the upload
from the Premiere Elements built in YouTube feature?
The typical troubleshooting steps for this type of issue start with
1. Refresh Online Services in Premiere Elements Editor Edit Menu/Preferences/Web Sharing
2. Export your Timeline to a file saved to the computer hard drive and then upload that file from there to YouTube at the YouTube web site.
Does that work whereas the feature built into Premiere Elements does not?
Also clear the Cached Web Content under your browser's Options/Advanced/Network.
We will be watching for your progress.