A mod to display your name could look like this:
<?xml version="1.0" encoding="utf-8"?>
<Page Name="MyName" Size="365,30">
<Text DynamicData="/GameData.Self.Name" Font="/TextStyles.VeryLarge.VeryLargeStyle" Name="PlayerName" Size="365,30" />
</Page>
If you leave out the <Page></Page> tags you would get the error message you quoted.