How to use reference parameters usefully?

[SamiHawasli]

Hello all,

I am creating a parametric drawing and I've run across a problem. AutoCad lets you define reference parameters, a measurement from a driven object, but when i try to use those reference parameters in a function, I get an error. I'm not even using the reference parameter to drive another object, simply to calculate some ratio. Perhaps my syntax is wrong, or its just impossible to use a reference parameter in such a way?

Any help would be much appreciated,

Sami