Security settings on this doc prevent signing

I created a form with interactive fields. 1) in security settings it says "no security" 2) under Advanced, I "enabled usage rights in Adobe Reader" 3) opening the pdf in Reader X I clicked on the "Sign" button at the top 4) I get the "The security settings on this document prevent adding text ...." pop up in the Sign Pane. 5) I checked the security properties in Reader and it shows everything is allowed. ?????