Unabe to sign a PDF document (not a Form)

I am using Adobe Acrobat Reader DC to sign a PDF document (that is not a fillable Form).  All the steps work well.  I inserted my signature in the right place, and I added my name (in plain text) as well as a date.  Everything looks perfect. 

But as soon as I try to  SAVE or SAVE AS, everything I just inserted into the document disappears, I get an error message saying that and "Unknown error has occurred".  But then the system proceeds to ask me where I want to save the file.  I save it, but my signature and everything else I had typed in is still gone.   The process of saving the file always discards everything I have inserted.

I have tried this on 2 different Windows computers, one with Windows 7 and one with Windows 8..  Always the same error. Always unable to save the PD file with my signature.

I have tried it .while signed in to my Adobe account, and also when I was NOT signed in.  No difference. Same result.

Why can't Adobe Acrobat Reader DC save my signature?