A tweaked version of your suggestion worked. I think one of the issues was that I had not defined all variables.

One issue I have now is that I can run the code line by line, but when I run the whole code - which should generate e.g. 20 different presentations, it sometimes stops in the middle of the code and generates an error.

I'm not sure if error handling is the issue, but is seems weird to me that the code works fine line by line, but sometimes stops in the middle when i run long loops. Could it have to do with the amount of memory my excel can handle? Any solutions to this?