> I am learning MongoDB and found that I got "invalid operator: $elemMatch"
> whenever I use $elemMatch in the query no matter I follow the example in
> "Seven Database in Seven Weeks" or following MongoDB Advanced Query
> tutorial.  The followings are excerpt.
> > db.documents.insert( {
> ... Name: "name1",
> ... Identifiers: [
> ... { name: "manufacturer26", value: "abc123" },
> ... { name: "store5", value: "tty3" },
> ... { name: "factory3", value: "521" }
> ... ]
> ... } );
> > db.documents.find( { "Identifiers": {$elemMatch: { name: "store5",
> value: "tty3" } } } );
> error: { "$err" : "invalid operator: $elemMatch" }

> I have the most recent version (2.2.0) of MongoDB.  Did I miss something?  
> How do I get it to work?
> Thanks.