ASP.NET Master page DefaultButton override

[Salazarr]

I have a master page with a form element and the defaultbutton attribute set to a server-side ImageButton. On one of my pages I want to "override" the masterpage defaultbutton attribute by setting the Forms DefaultButton in the Page_Load event.i.e On mater page:\[code\]<form id="form1" runat="server" defaultbutton="btnSearch">....</from>\[/code\]On the page Page_Load event that "override" the master page attribute:\[code\]this.Form.DefaultButton = this.ibRecalc.ID;\[/code\]It errors with :\[quote\] The DefaultButton of 'form1' must be the ID of a control of type IButtonControl\[/quote\]I am using image buttons which implements IButtonControlAny ideas of what I might be doing wrong or a different way to approach the problem?Thanks