It works but I don't know why ... could someone help me

<table cellspacing="0" cellpadding="0" border="0" background="/pix/content_trennlinie.gif" width="100%"><tr>
<td valing="top"><img height="25" border="0" width="100%" src="/pix/0.gif" alt="" /></td>
</tr></table>

FCKConfig.ToolbarSets["Default"] = [
   ['FitWindow','Source','-','-','Preview'],
   ['Cut','Copy','Paste','PasteText','PasteWord','-','Print'],
   ['Undo','Redo','-','Find','Replace','-','SelectAll','RemoveFormat'],
   '/',
   ['OrderedList','UnorderedList','-','Outdent','Indent'],
   ['JustifyLeft','JustifyCenter','JustifyRight','JustifyFull'],
   ['Link','Unlink','Anchor'],
   ['Image','Flash','Table','Rule','InsertHrTable','Smiley','SpecialChar'],
   '/',
   ['Style','FontFormat','-','Bold','Italic','Underline','StrikeThrough','-','Subscript','Superscript'],
   ['TextColor','BGColor'],
   ['ShowBlocks']
];

FCKConfig.Plugins.Add( 'InsertHrTable', 'de,en' );

// Define the command.
var FCKInsertHrTable = function() {
   this.name = 'InsertHrTable';
}

FCKInsertHrTable.prototype ={
   Execute:function() {
      FCKUndo.SaveUndoStep();
      FCK.InsertHtml('<table cellspacing="0" cellpadding="0" border="0" background="/pix/content_trennlinie.gif" width="100%"><tr><td valing="top"><img height="25" border="0" width="100%" src="/pix/0.gif" alt="" /></td></tr></table>') ;
   }, GetState:function() {
      if (FCK.EditMode!=0) return -1;
      return FCK.GetNamedCommandState('InsertHrTable');
   }
}

// Register the HrTable tag command.
FCKCommands.RegisterCommand( 'InsertHrTable', new FCKInsertHrTable() ) ;

// Create the 'InsertHrTable' toolbar button. 
// FCKToolbarButton takes the following arguments: CommandName, Button Caption 
var oInsertHrTable = new FCKToolbarButton( 'InsertHrTable', FCKLang['DlgInsertHrLineBtn'] ) ; 
oInsertHrTable.IconPath = FCKPlugins.Items['InsertHrTable'].Path + 'icon.gif' ; 
FCKToolbarItems.RegisterItem( 'InsertHrTable', oInsertHrTable ) ;



//var FCKRuleCommand=function(){
//   this.Name='Rule';
//};

//FCKRuleCommand.prototype={
//   Execute:function(){
//      FCKUndo.SaveUndoStep();
//      FCK.InsertElement('hr');
//   },GetState:function(){
//      if (FCK.EditMode!=0) return -1;
//      return FCK.GetNamedCommandState('InsertHorizontalRule');
//   }
//};

var FCKInsertHrTable = function() {
   this.name = 'InsertHrTable';
}

FCKCommands.RegisterCommand( 'InsertHrTable', new FCKInsertHrTable() ) ;

this.name = 'InsertHrTable';

FCKInsertHrTable.prototype ={
   Execute:function() {
      FCKUndo.SaveUndoStep();
      FCK.InsertHtml('<table cellspacing="0" cellpadding="0" border="0" background="/pix/content_trennlinie.gif" width="100%"><tr><td valing="top"><img height="25" border="0" width="100%" src="/pix/0.gif" alt="" /></td></tr></table>') ;
   }, GetState:function() {
      if (FCK.EditMode!=0) return -1;
      return FCK.GetNamedCommandState('InsertHrTable');
   }
}