Grasshopper Solid Union Not Working

Hi everyone. I’m very new to Grasshopper so this issue is probably caused by some simple step I’m forgetting. I’m trying to create some definitions that I can later on copy and paste to let me quickly model background buildings for my architectural renders, which often need to be in the correct location.

This one is supposed to let me use an input curve and distribute a window with mullions along it.

In order for this to really be useful, I want it to come into rhino as just two objects: the window with mullions, and a backing surface that will appear as the windows. Otherwise I’ll have to change the material of every separate part individually in Rhino.

All of the mullions are solid Breps. The top and bottom of the window frame are also Breps. All of them overlap and line up, and if I bake what I have and use the Boolean union tool in rhino it works, so I know it’s possible.

I’m sure there is a cleaner way to accomplish my end goal than my current definition, but as I said I’m very new so this was the best I could do at this stage. Hopefully someone has some tips of how to fix my problem!

Thank you!!

image Variable_mullion_02

you might want to upload a file for people on here to be helpful
by looking at your screenshot, I’m guessing the tree structure might be the problem going into SUnion (19.5 KB)

You’re right that probably would be helpful! Here is my file.

According to your screenshot, the wire display from the output of Merge is shown in a grey double-line dash wire type which means it contains a data structure(Multiple branches and items, that is). That’s why Solid Unionnot gonna work.
Try to flatten the "B"input of the Solid Union.

That worked perfectly! Thank you so much for your help and thanks to Will as well!