Button in Ribbonbar der Site Permission einfügen

Hallo Zusammen,

ich möchte einen Button in einem neuen Bereich  in der Ribbonbar der Site Permission einfügen. Ich habe bis jetzt folgenden Code:

<CustomAction Id="TestButtonID" Location="CommandUI.Ribbon">
    <CommandUIExtension>
      <CommandUIDefinitions>
        <CommandUIDefinition Location="Ribbon.Permission.Scaling._children">
          <MaxSize Id="Ribbon.Permission.Customs.MaxSize" Sequence="15" GroupId="Ribbon.Permission.Customs" Size="LargeLarge" />
        </CommandUIDefinition>
        <CommandUIDefinition Location="Ribbon.Permission.Groups._children">
          <Group Id="Ribbon.Permission.Customs"
                   Sequence="101"
                   Command="Perm_Customs"
                   Description=""
                   Title="Work Order"
                   Template="Ribbon.Templates.Flexible2">
            <Controls Id="Ribbon.Permission.Customs.Controls">
              <Button
               Id="Ribbon.Permission.Customs.Add"
               Command="TestButton"
               Sequence="10"
               Image16by16="/_layouts/$Resources:core,Language;/images/formatmap16x16.png" Image16by16Top="-192" Image16by16Left="-160"
               Image32by32="/_layouts/$Resources:core,Language;/images/formatmap32x32.png" Image32by32Top="-160" Image32by32Left="-288"
               LabelText="WorkOrder"
               Alt="WorkOrder"
               ToolTipTitle=""
               ToolTipDescription="Work Order how to manage Permissions"
               TemplateAlias="o1"/>
            </Controls>
          </Group>
        </CommandUIDefinition>
      </CommandUIDefinitions>
      <CommandUIHandlers>
        <CommandUIHandler Command="TestButton"
          CommandAction="javascript:window.open('http://www.google.de','_blank')" />
      </CommandUIHandlers>
    </CommandUIExtension>
  </CustomAction>

Leider wird das JavaScript nicht ausgeführt und ich weiss nicht warum, hat da jemand eine Idee?

Grüsse