Hi Alfonso,

Thank you for the helpful reply, the attachment you provided had indeed solved the error.
This bring me to some other questions (I apologize if these questions have been addressed elsewhere, I just couldn't find one that is specific):
1) A voxel-to-voxel connectivity matrix is obviously very large in size (which, to my knowledge, has been stored in its eigenvalue/vector equivalent), is there anyway I could access this matrix, extract it out as matlab structure, in order to do further processing on it? If so, if I do a surface-based analysis, would each of the row (represents 1 voxel or source point) corresponds to a node on the fsaverage surface (or the subject-specific pial surface?) in the same indexing order?
2) If (1) cannot be done, then down-sample the functional volume into ~1000 voxels to use as ~1000 ROIs seems to be the answer (as the connectivity matrix is output for ROI-to-ROI analysis), if so, can I do it in subject-specific surface-based manner (using "label" files in Freesurfer "label" folder)? I tried using ".annot" from Freesurfer (../label/lh.aparc.annot) as ROI but received this ERROR:


ERROR DESCRIPTION:

Error using horzcat
Dimensions of matrices being concatenated are not consistent.
Error in conn_annot2nii (line 50)
data=[log.data{ifile(1)}(:) log.data{ifile(2)}(:)];
Error in conn_getinfo (line 13)
filename=conn_annot2nii(filename);
Error in conn_file (line 3)
[V,str,icon,filename]=conn_getinfo(filename);
Error in conn (line 1543)
V=conn_file(deblank(filename(1,:)));
Error in conn_filesearchtool (line 131)
if length(h.callback)>1, feval(h.callback{1},h.callback{2:end},names); else, feval(h.callback{1},names); end
CONN v.15.g
SPM12 + DEM FieldMap MEEGtools
Matlab v.2013a
storage: 324.1Gb available

Again thank you very much for your assistance, this is a wonderful toolbox to use.
Best,
Thinh Nguyen