Dear Alfonso,

Thank you for your quick and kind response.
I have done your suggestion;
- I tried to start over all the process from adding ROIs again, running the preprocessing and denoising procedure again (ROIs not included as confounds; followed default setting), then ran the first-level analysis and it gives the same error message.
- So, Step 1/3: ROI-to-voxel first-level analyses went well, Step 2/3: ROI-to-ROI first-level analyses went well, and Step 3/3: Preparing second-level analyses gives an error.
Where should I send a conn_*.mat file?