No luck with pluck:

<code>alert(_.pluck(options.collection.models, "pk"));</code>
returned
<code>,,,,,,,,,,,,,,,,,,,</code>

<code>alert(_.map(options.collection.models, function(model) {
                return model.get('pk');
            }));</code>
returned
<code>282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301</code>

Am I missing something here?