Cosmosworks expressions

I'm doing some analysis in CosmosWorks for the first time. I've
played around enough to be reasonably comfortable with setting up and
running a study, but now I'm trying to go ahead and do some actual
work. I have multiple cases to study (static load at maximum weight,
fatigue load at nominal design weight, for two different
orientations), so I linked in parameters for the load components.

The part that I can't figure out is the syntax used for expressions
within a parameter. I've tried, in the expression box, a*b, "a"*"b",
c = a * b, "c" = "a" * "b", etc; for any of these cases, when I hit
"OK" or "Apply", nothing happens. The help, of course, has not been
helpful; the only thing I've gotten from there is that my units need
to match, which they do - I've also tried various unitless parameters
and actual numbers, with no success.

Here's what I'd like to have ideally:
-one parameter for the weight
-unitless G coefficients for X,Y,Z, which I would change for each
case.
-three component force parameters, found by multiplying the above
inside expressions, which I would use as the linked values for my
load.

In this instance, I just went ahead and defined the force components
directly, but it'd save time on a larger study to be able to adjust
the weight and have the forces calculated automatically.

Has anybody successfully used expressions to define parameters
before? Am I missing something obvious?