Problem in IE 9 : Unable to get value of the property 'init': object is null or undef

I have rendered some ExtJS progress bars to divs in my web page.

It works fine in Chrome, FireFox and IE10 but IE9 is making problems.

I can't see the progress bars and I get the following error :

"Unable to get value of the property 'init': object is null or undefined"

In the ext-all.js file the following line is causing the error :

Ext.supports.init()

"supports" in undefined

What may be the problem?

Problem in IE 9 : Unable to get value of the property 'init': object is null or undef