Read Speed with the IBT Class #39

Hello, sorry if this is a silly question.
Python is new to me, and I'm just an engineer trying to perform some data analysis, not a programmer.

I'm attempting to extract data, such as speed, from an IBT file. According to the example in the tutorial, this should work. Reading the CarSetup, as mentioned in a previous question, works fine, but unfortunately, the speed extraction does not seem to be functioning: IndexError: list index out of range

Thank you for your great work!