Hi Paul

Thanks for the clarification :)

I put the Users/ as my directory but that is not the directory I have all my files in. I just did that to simplify the troubleshooting (maybe it ended up causing more confusion).

So now that I fixed the file name for the argument, it ran with no trouble in finding the vector files.

But now I'm getting another error:

SEARCHING for scalar files with prefix: /Users/dti-afni
FINDING: **FATAL ERROR: Can’t open dataset ‘/Users/dti-afni-trackid_det.niml.opts’

I'm not sure if you'd be able to help out with that.

I hope to hear back soon. Thanks