asp.net 2.0在使用了mater page的情況下Form defaultbutton無法設定的問題

問題如題

我嘗試了下列方法，在頁面程式中加入：

1    protected override void OnInit(EventArgs e)
2    {
3        base.OnInit(e);
4        Page.Form.DefaultButton = "btnSearch";
5    }

但是頁面提示錯誤,宣告失敗
 

The DefaultButton of 'form1' must be the ID of a control of type IButtonControl.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: The DefaultButton of 'form1' must be the ID of a control of type IButtonControl.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

不知道有沒有哪位高人有好的解決方案？