prototype.registerCallback is not a function

[arunabhdas]

Using firebase-element with Polymer 1.2.1 and getting the following error

Uncaught TypeError: prototype.registerCallback is not a functiondesugar @ polymer-micro.html:74window.Polymer @ polymer-micro.html:58(anonymous function) @ firebase-element.html:132
input-header.html:52 Login was clicked

[arunabhdas]

The error goes away if I remove the following line

from elements.html

[VandeurenGlenn]

@arunabhdas are you using the correct one? for Polyemer 1.0 you need repo