or
I have Tried a test to verify the values loaded in the dropdown from the site "http://www.asp.net/ajaxlibrary/AjaxControlToolkitSampleSite/cascadingdropdown/cascadingdropdown.aspx"
When I execute the recorded script throws error at step 4 where it doesn’t throws error at step 2 (Step 2 and Step 4 are similar).
The issue happens only in IE9 but it works fine when we switch to compatibility mode.
Attached the sample project.