Cannot delete glossary entry

I'm trying to delete a glossary entry. When I click on Delete, Edit, Add, or Move, I get this error message: "The current line is not a glossary entry. First place cursor on glossary entry before retrying." Have deleted many entries, first time this has happened. Interestingly, when I open this glossary (and several others just in case) in Notepad, this entry is not in the list; was hoping to delete it from there. Any ideas on how to get rid of it? Other entries are working fine.