The problem is that you cannot tell the product to use a sweep on a structure that is build with a script. Instead you need to use a script. If you copy and paste your script to notepad and then take your design and check “Generate User Script” in the Parameter Sweep window it will generate a script that will iterate through your parameter sweep and generate the output files (they are .psr files just open them in notepad or similar product). To include your build script you add a function to the generated script for building and you make a call to the script in the for loop. Then run the simulation using the script.
I have an example of this using your design file attached.
Scott