Default Radio Button Not Selected

Hi All,
I need to reset my radio button, back to a default setting, and return the focus to this control. When I run the following code, it doesn't select the item I want. How do I refresh my radio button, in order to reflect the new default selection?
        // Reset Radio Button
        this.RadioButtonList1.SelectedValue = "5";
        this.RadioButtonList1.Focus();

Thanks.



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