Jquery loader not activating

I've got the following... http://jsfiddle.net/yUVF4/3/ Basically it's just a form which when the button is pressed a loadi开发者_运维技巧ng screen should appear using the javascript there and the resource I've added jquery.loader.js. However, It's not working and I can't seem to grasp why. Anyone got any ideas?

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Just add div wrapper in the content parameter of the plugin, it works

content:'<div>Loading...</div>'

See jsfiddle