I tried the following in form load, it looks like is not working

private void Form1_Load(object sender, EventArgs e)
{
//check for the operating system to change the frame
string operatingSystem = System.Environment.OSVersion.ToString();
if (operatingSystem.Contains("Microsoft Windows XP"))
{
nuiManagerController1.PredefinedFrame = PredefinedFrame.Office2007Blue;
}

How to change the frame at run time?