Advancing Python in Unreal Engine part 2

I'm continue to make some progress in this area. The next tasks have to do with material instancing. This will make it easier to create new and different materials with the required data. I already have the code set up to place a new instance into a project:

The next step is creating code that makes more instances based on how many textures are4 selected, but the function they tell you to use seems to be insuficient for what's needed and only produces one instance still while presenting a misterious error message at let to what I know. Here's the new function:

And this is the error message that comes up:

I'll keep working on this and see what I can make.