attrForSelected as property name works, attr-for-selected doesn't

[vihai]

Hello,

I'm starting to experiment with Polymer and webcomponents so please excuse my ignorance.

I created a iron-selector and it only works if I specify a property using the camel case for attrForSelected. If I use the dashed format it does not work, despite the documentation saying otherwise.

I'm using iron-selector 1.5.2 pulled with bower and Polymer 1.7.0

What may I be doing wrong?
Thank you