afni.nimh.nih.gov

Does a file called "dti-afni-trackid_det.niml.opts" exist in that directory? If so, I think it is confusing 3dTrackID, which wants to open all files with the prefix supplied to "-dti_in ...". It is expecting only volumetric files (NIFTI or BRIK/HEAD) to have that prefix-- I bet if you rename it, then it should be fine. (*Assuming that it is currently existing... otherwise, I'd have to think more. Eek.)

--pt