FitLins and multiple sessions and tasks

Dear all,

I would like to use fitlins to analyze our longitudinal data of two groups, patients and controls, consisting of 3 tasks each performed at 3 different timepoints (sessions).
All data are in BIDS format and preprocessed with fmriprep using the longitudinal flag. I am now stuck with the statistical model, where I want to use fitlins if possible. I do understand that I can use split to separate the sessions and how to use repeated runs according to the provided examples. At the moment I am stuck with an “No functional images that match criteria found.” but I am wondering …

  1. how to specify more than one tasks I want to model and compare. The tasks are identical, i.e. have the same three different events (trial_type), but have different instructions.

  2. how to specify or conduct comparisons between the two groups?

  3. are covariates possible and in particular, can I do a comparison trial_type vs. respiration?

Thanks in advance,