AutoCAD Inventor :: ILogic Rule To Populate Finished Material Size Based On Model Geometry Selection

I created the following user parameters:

-Thickness
-Width
-Length
-Dia

I then created a Custom iProperty which consisted of the following "formula":    Finished Material Size = <Thickness> x <Width> x <Length> Lg.

eg. of Finished Material Result :        Finished Material Size = 6 x 25 x 300 Lg.

The problem comes up when dealing with diametrical components as the above formula will only populate for square or rectangular parts. Which would work if I could use iLogic code to populate the Finished Material Size iProperty. I have tried but failed.

First I created another user parameter called "Geometry Type" which has a drop down selection of either "DIA" or "SQUARE, RECTANGULAR".I then created the following iLogic code to set 0 as the value for the "unused" size parameters

 If PART_GEOMETRY = "DIA" Then WIDTH = "0"If PART_GEOMETRY = "DIA" Then THICKNESS = "0"If PART_GEOMETRY = "SQUARE, RECTANGULAR" Then DIA = "0"
 The part I just can't get to work is as follows.

I need some iLogic code which will populate the "FINISHED MATERIAL SIZE" custom iproperty with one of the following based on my "GEOMETRY TYPE" selection. "DIA" would return the following to "FINISHED MATERIAL SIZE":      = Ø <Dia> x <Length> Lg.

While "SQUARE, RECTANGULAR" would return the following to "FINISHED MATERIAL SIZE":     = <THICKNESS> x <WIDTH> x <LENGTH> Lg.I tried the following code but it does not work:

If PART_GEOMETRY = "DIA" Then iProperties.Value("Custom", "FINISHED MATERIAL SIZE")= "Ø"DIA "x" LENGTH "Lg."If PART_GEOMETRY = "SQUARE, RECTANGULAR" Then iProperties.Value("Custom", "FINISHED MATERIAL SIZE")= THICKNESS "x" WIDTH "x" LENGTH "Lg."