The reason you are getting 'Not eTA eligible'..... for the link which YOU posted..... is that your sought information on eTAs for Mexican citizens. Until November 30, 2016, Mexicans must apply for TRVs.JimE2013 said:http://www.cic.gc.ca/english/visit/eta-start.asp
Click "apply for an eTA." Select "Mexico." Select "no" for the question "Are you a lawful permanent resident of the United States with a valid alien registration card (Green Card)?" Click "next." The result? "Not eTA-eligible"
As for question two of your post, let me search my bookmarks. It's here somewhere.
Do check the link I had posted earlier..... and you will see what all of us have been saying is correct + you will see the explanation/dates from.CIC below the result