How do I write an Autoit script to uncheck a box on a specific URL?

I have a list of specific URLs.

On each of the webpages, there are a selection of check boxes. I want to uncheck a particular check box.

I've tried putting together this script:

Local $oIE = _IECreate("http://ift.tt/1JBwtUF") ControlCommand("", "&id=1430510", "chkCurrentProperty", "UnCheck", "")

The script takes me to the page correctly but does not uncheck the box. What am I doing wrong?