Visual Studio C-Sharp Word Add-In - Text zu Fußzeile hinzufügen

<?xml version="1.0" encoding="UTF-8"?>  
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui" onLoad="Ribbon_Load">  
  <ribbon>
    <tabs>
      <tab id="tab1" label="FUSSZEILE">  
        <group id="group1" label="Hinzufügen">  
          <button id="button1"   
                  label="button1"  
                  screentip="Screentip"   
                  getImage="Btn1_GetImage"   
                  supertip="Supertip"    
                  size="large"   
                  onAction="OnButton"/>  

          <button id="button2"  
                  label="button2"  
                  screentip="Screentip"  
                  getImage="Btn1_GetImage"  
                  supertip="Supertip"  
                  size="large"  
                  onAction="OnButton"/>  
        </group>
      </tab>
    </tabs>
  </ribbon>
</customUI>

protected override Office.IRibbonExtensibility CreateRibbonExtensibilityObject()
        {
            return new RibbonFooter();
        }

public Bitmap Btn1_GetImage(Office.IRibbonControl control )
        {
            return new Bitmap(Properties.Resources.footer);
        }

public void OnButton(Office.IRibbonControl control)
        {
            //Add Footer: https://msdn.microsoft.com/en-us/library/ms178795.aspx
            var addIn = Globals.ThisAddIn.Application.ActiveDocument;
            
            foreach (Word.Section wordSection in addIn.Sections)
            {
                Word.Range btn1Range = wordSection.Footers[Word.WdHeaderFooterIndex.wdHeaderFooterPrimary].Range;
                btn1Range.InsertAfter("");  
                btn1Range.Font.Size = 20;
                btn1Range.Font.ColorIndex = Word.WdColorIndex.wdBlue;

                switch (control.Id)
                {
                    case "button1":  
                        btn1Range.Text = "Test 1    ";  
                        break;
                    case "button2":  
                        btn1Range.Text = "Test 2    ";  
                        break;
                }
            }
        }