Static resources inside TableView using XAML doesn't work

Hi,
There is no way to find a resource defined inside a ContentPage.Resources if you call it from a tag inside a TableView. Maybe I'm doing something wrong but this code doesn't work for me:

      <ContentPage.Resources>
        <ResourceDictionary>
          <x:String x:Key="caption" >Hello there!</x:String>
        </ResourceDictionary>
      </ContentPage.Resources>

    <TableView>                 
        <TableRoot Title="x">
            <TableSection Title="y">
                <TextCell Text="{StaticResource caption}" />
            </TableSection>
        </TableRoot>
    </TableView>

Thanks in advance!