Problem with adding GCA directory

Dear Experts
Hi

I am trying to find the path coefficients between eight DMN regions and my study onsists of 8 patients and 8 controls.By following the GCA tutorial  I put my subjects in a folder with "subject001,subject002..." subfolders,however, as I wanted to add the data directory the following error showed up:
"There is no data or non-data in this directory please re-select". How could I solve this problem?
Secondly,since GCA could only calculate path coefficients between 3 regions  then how should I feed 8 regions to GCA?
Many thanks in advance.

Kind Regards,
mahsa

Dear Experts
I was able to tackle the directory problem.However, after selecting 2 ROIs for a subject and clicking the compute button the following error occurs:
"Error using rest_ReadAnalyzeImage(line53)
please check whether the hdr file exists."
Since both hdr/Img files for the ROIs are available in the corresponding folder,What could cause this problem?
Many thanks in advance.

Best,
mahsa

 Is your ROI file Analyze Format? REST used rest_ReadAnalyzeImage to read it and then met error. Please check your ROI first. You may use MRIcronN to open it, if opens it correctly without any popout warning msg, you can add them into GCA GUI.

Dear ZHANG

Thank you so much for replying. ROIs seem to be fine and I could open them using mricro,mricron....However, the problem still exists.
Secondly,since GCA only could calculate path coefficients between 3 ROIS(am I wrong?) How should I feed 8 regions to GCA?
Many thanks in advance.

Best,
mahsa

 more ROIs should be ok for GCA in REST ... 
 The ROI seems to be right and good, so would you please try using voxelwise GCA instead? If it works correctly, this ROI will be good. 

Dear ZHANG
Thank you so much for your time.
I tried changing the ROIs names.However, the error is changed to:
"Exception occured:
Attempted to access R(1);index out of bounds because numel(R)=0"
I really appreciate your help.