Adding Comments In Lightroom 5

I am using Lightroom 5 and under the Comments section it says - "Selected service does not support comments" - Why???? I would really like to add comments to many of my photos - I try to use tags and keywords - BUT sometimes I just want to add comments!!! Why is this section even there if it is not supported? Is there an add-on or another program I need? How can I add comment to my photos? HELP!!! . . . Thank you :-)