Page 643 - C# Code Block
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
WebPartDisplayMode wpDisplayMode = Webpartmanager1.SupportedDisplayModes(DropDownList 1.SelectedValue.ToString()); /* syntax error use of brackets... check next statement for correct syntax */
WebPartDisplayMode wpDisplayMode = Webpartmanager1.SupportedDisplayModes[DropDownList1.SelectedValue.ToString()]; /* corrected statement*/

Webpartmanager1.DisplayMode = wpDisplayMode;
}

It works... Thanx