Preview toolbar is grayed out

I'm trying to add my signature to documents using Preview. I have created a signature using the built-in camera, but can't insert it anywhere.

My Preview toolbar is grayed out so I can not use the "toolbox/markup" icon or the "pen/signature" icon. If I click on Tools, Annotate, & finally Signature, the signature block appears on the document w/ the newly created signature in the blue box. According to the website, I should be able to click & drag the signature, resize it, etc. But I can't do either of those. No matter what I click on i that signature bloc, nothing happens. The signature won't insert into the document and no re-sizing/dragging, etc happens. Any ideas ? Thnx