When running the script nii_nii2mat after selecting the images to be converted and modality which is 1 (lesion) in this case, we obtain the following error: 
Error in nii_nii2mat (line 97)
new = nii_roi2stats(ROIname,hdr,img,statfield);

What should we change for this to work?

Thanks in advance for your help,
Best,
M.