sharepoint 2010 conditional formatting in discussion board not working

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ASP.NET

SharePoint2010

Hi All, please help me out.
I'm working on a project built in sharepoint 2010 enterprise. I have a discussion board, with 1 subject(default view) top tier and 1 Flat view.
Using conditional formating in default standard view, I've easily hidden reply column(with condition $thisNode/@ItemChildCount > '0') when needed. But It does not work in Flat view.
I have also created Threaded view. But so far I wasn't able to be succesful in Flat view and Threaded View.
In Flat View and Threaded view, no conditional formating(tried many condition on many html tag for testing) works. I don't know whether its a SharePoint bug, or there are any thing else which needed on particularly for Flat view or threaded view.