HI Caroline, thanks for posting.
Have you saved the followup dataset to a .dta file?
If so, double check you are pointing to the right location on your computer. You might have to use something like "data/followup.dta" rather than "followup.dta".
If so, double check you are pointing to the right location on your computer. You might have to use something like "data/followup.dta" rather than "followup.dta".