Adobe Acrobat Reader - Cannot save my PDF - Got this error message.

[Sharon5C94]

I have a macbook pro. When i tried to save the PDF that i highlighted, I got this error message: "

The document could not be saved. The file may be read-only, or another user may have it open. Please save the document with a different name or in a different folder."

What should I do?

[Sharon5C94]

I then tried to save it with a different name and in a different folder and got this error  "

The document could not be saved. A file error has occurred."