Dimension driven by custom property value?

Hi there,

Is it possible to use a custom property (value) to drive a dimension? It looks like it can be done, but maybe I'm doing something wrong.

Here's the process I'm following:

1) I've created a custom property, Stroke, which is numerical.

2) In a sketch, I try to link the dimension value to this property.

3) After selecting the custom property, it prompts me to create a global variable called "Stroke". (I can't see any way around this.)

The problem is that the global variable "Stroke" isn't linked at all to the property "Stroke". On creation you can assign any value to the global variable, and changing one value does not affect the other. 

Am I doing this wrong, or is there any way to do what I'm trying to do, maybe within a design table (but having the dimension driven by a custom property)?

Thanks for any help with this.

SolidworksSketching