I have some problems adding a new custom button to the ribbon. As explained in the sharepoint 2010 SDK (How to: Modify the User Interface Using Custom Actions), i've created a visual studio project and copied the xml code which should create the new button. Here is the code:

```
<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
  <CustomAction Id="ListViewCustomization" Location="CommandUI.Ribbon.ListView" RegistrationId="101" RegistrationType="List" Title="List View Ribbon Customization">
    <CommandUIExtension>
      <CommandUIDefinitions>
        <CommandUIDefinition Location="Ribbon.Documents.Share.Controls._children">
          <Button Id="ListViewButton" Command="ListViewButtonCommand" Description="Go to Settings" LabelText="Site Settings" TemplateAlias="o2" Sequence="93"/>
        </CommandUIDefinition>
      </CommandUIDefinitions>
      <CommandUIHandlers>
        <CommandUIHandler Command="ListViewButtonCommand" CommandAction="/_layouts/settings.aspx" />
      </CommandUIHandlers>
    </CommandUIExtension>
  </CustomAction>
</Elements>

```

I've checked the site settings of my site collection, and the new feature results activated, but no new button around. 
Am i missing some steps?