Why does my property not expand in the request?

I'm puzzled why I cannot get a property to expand in my request; I think I've done everything (but obviously not the correct thing) right, so I'm hoping someone can provide me some guidance as far as what I'm doing incorrectly .

I've attached the .jpg showing my setup:

1. I have a property named "CityName" defined/valued in a TestCase

2. I have a request where I want the value of the property to expand when executed

3. The property did not expand to the value of the property; it resolves to an empty string.

The request is a simple method on: http://www.webservicex.net/MedicareSupplier.asmx

I'm just trying to understand the mechanics of defining a value in a property using it in a request so I can move on to scripts that calculate different property values.