I just wanted to give an update to this problem... The solution was fingered out by a Dell guy, so good job for him! Anyway, it appears I had too many slashes. Once removed it works great!
Code:
<item type="rect">
<pos anchor="n" x="50%" y="10" width="box" height="box"/>
<box>
<item type="label">
<normal font="Sans 14" color="#ffffff"/>
<text>
Insert the text of your warning banner here.
</text>
</item>
</box>
</item>