From the Reference Manual:
You appear to have used the name of a Highlighter as the Highlight Property, instead of the name of a property that contains the name of a Highlighter.
The Highlighter Property should contain the name of a Global Property (probably a Zone GP attached to this zone) that contains ‘Hampton’ as its value.
It is designed so that you can change the current highlighter of a zone dynamically by changing the value of the Highlighter property.
Regards.