OK button on Opportunity Close dialog is not working !

I am trying to open close opportunity dialog with javascript in Opportunity form.

But when i click on OK button it does not close the opportunity record.

 var url = serverUrl + '/SFA/opps/dlg_closeopp.aspx?dType=1&pID=' + Id + '&pType=3&won=false';

any parameter in url i am missing??

Thanks.