ToolTip does not show for CheckBox control in C#

Why does the ToolTip not show for CheckBox controls in C# WinForms? Is this a known issue or am I doing something wrong? This is my code:

     // create the ToolTip
     ToolTip toolTip1 = new ToolTip();

     // Set up the delays for the ToolTip.
     toolTip1.AutoPopDelay = 100;
     toolTip1.InitialDelay = 100;
     toolTip1.ReshowDelay = 100;
     toolTip1.ShowAlways = true;

     // Set up the ToolTip text for the Button and Checkbox.
     toolTip1.SetToolTip(checkBox, "TEST TOOLTIP!");