System.ArgumentException: Object of type 'System.DBNull' cannot be converted to type 'System.String'.
   at NVelocity.Runtime.Parser.Node.ASTMethod.Execute(Object o, IInternalContextAdapter context)
   at NVelocity.Runtime.Parser.Node.ASTReference.Execute(Object o, IInternalContextAdapter context)
   at NVelocity.Runtime.Parser.Node.ASTReference.Render(IInternalContextAdapter context, TextWriter writer)
   at NVelocity.Runtime.Parser.Node.ASTBlock.Render(IInternalContextAdapter context, TextWriter writer)
   at NVelocity.Runtime.Directive.Foreach.Render(IInternalContextAdapter context, TextWriter writer, INode node)
   at NVelocity.Runtime.Parser.Node.ASTDirective.Render(IInternalContextAdapter context, TextWriter writer)
   at NVelocity.Runtime.Parser.Node.SimpleNode.Render(IInternalContextAdapter context, TextWriter writer)
   at NVelocity.Template.Merge(IContext context, TextWriter writer)
   at UI.Template.NVelocityHelper.Display(String templatFileName)
   at Web.Default.Page_Load(Object sender, EventArgs e)