[System.ComponentModel.Description("Mark this field as invalid, using msgTarget to determine how to display the error and applying invalidClass to the field's element.")]
public virtual void MarkInvalid( 
   System.string msg
)

Parameters

msg

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference