ASP.NET - SetFocusOnError in required field validator not working for firefox

Hi,
In my project I am using validation controls and set showMessageBox="true" for validation summary control.
when I click submit button without enter required fields,Validation summary displaying in message box. when i click ok
focus does not set to the first failed required field in Firefox while it is working in IE and google Chrome.

Please solve this issue.
Thanks in Advance.

do one thing go to your web.config and set "mode" of "xhtmlConformance" to "Legacy"

<xhtmlConformance mode="Legacy"/>