"Unable to get value of the property 'split': object is null or undefined" error in IE

I am trying to use ASP.NET AJAX Toolkit's MaskedEditExtender Control (with MaskedEditValidator) in my web application. The control works fine in Google Chrome but开发者_开发问答 IE9 throws a "Unable to get value of the property 'split': object is null or undefined" error while loading the page that contains the MaskedEditExtender controls.

The Visual Studio debugger breaks into MaskedEdit.MaskedEditBehavior.debug.js at the following statements:

var partdt = arr[0];
var parttm = arr[1];
if (parttm.split(" ").length == 2) 
{
    parttm += " " + parttm.split(" ")[1];  // breaks here
}
partdt = this.ConvFmtDate(partdt,loadFirst);

I have also tried using the

<meta http-equiv="X-UA-Compatible" content="IE=8" />

as mentioned in this post but it did not work. I am also using JQuery 1.4.2 in my application. Any Ideas??

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• Did you recently convert your web application from MVC 2 to MVC 3?
• If so, are you using unobtrusive Javascript?

Here's an excellent explanation from Brad Wilson.