Just can't understand tags

I just don’t understand DT’s tags…

So I have a document in a group (folder?). I do an info on it, and in the tags field, I see the grey name of the group, and I have 4 blue names of tags. Why, if I select the corresponding tag name in the LH column, I don’t see the document with the same tag?

Also, if I add a new tag in the info field, why doesn’t the document appear in the corresponding tag (LH column) list?


Over here, selecting a tag in the Tags group shows all documents to which that tag is assigned.

Maybe if you posted a screen shot we could see what you see?