HTML Text Editor not updating the text

Hi im usig Winnthusiasm.HTML editor,

<cc1:HtmlEditor ID="txtNote" Height="200px" Toolbars="Select#Format,Select#Font,Select#Size:ForeColor,BackColor;Bold,Italic,Underline:Left,Center,Right,Justify|OrderedList,BulletedList|Indent,Outdent|Rule|Subscript,Superscript:"
                                        runat="server" ToggleMode="None" />

and trying to Update text to DB but not it is bringing Null to

 businessUnitEntity.Notes = txtNote.Text.ToString(); 

Can some one suggest me any events like texchange or some thing i need to work out?