Red x in square

[Guest]

When I click on a link to see a .pdf file, all I get is a red x in a square.
I have the latest Adobe Reader, so I can't understand why I can't see the
..pdf files. Any suggestions?

 

[Mark L. Ferguson]

The Adobe add-on for IE must be enabled at IE, tools menu, "Manage AddOns"

 

[Guest]

I went there, but there was no add-on that listed Adobe. How can I list it?
Thanks for your help

 

[Mark L. Ferguson]

Reinstall the Adobe reader software, and it puts in the add-on for IE.