I am rendering a grid in my project.

On firefox, this code works fine.
However in IE 7 I get the following error:

'undefined' is null or not an object

I believe the error is occuring on Line 239 in ext-all.js and the following section is highlighted:
if(typeof _1[i].dataIndex=="undefined")

I feel as if I'm not providing enough information for you guys to help me with my problem, let me know what else I should provide!!