Issues with gravity

[2d platform game](file:///E:/cav/legend/launcher.html)
Hello. I’m using Phaser 2 and I’m trying to collide between the player and the platform, but the result gave me an error message “Unable to get property ‘hasOwnProperty’ of undefined or null reference”.

Any advice on how to do it?

http://phaser.io/examples/v2/arcade-physics/sprite-vs-sprite