Dear FSL Experts, I am attempting to run FDT registration after completion of bedpost. Within the registration window i have my BedPostX directory set to the Bedpost file that was created. In main structural image I have it set to my output file after doing BET on the T1 image - the filename is T1_BET.nii.gz The standard space is set to the default which is MNI152_T1_2mm_brain Both Main Image and Standard Space are checked however when running this I get the following errors. Errors: Image Exception : #22 :: ERROR: Could not open image /Users/Albert/Desktop/DICOM...../T1/libc++abi.dylib: terminate called throwing an exception Errors: Could not open matrix file /Users.../xfms/diff2str.mat Cannot read input-matrix Error: Cannot read input-matrix I believe that the problem is with the Main Structural Image. Which image should be used here? Thank you! -- David B. McCoy Peace Corps Volunteer, 2011-13 Africa- Mali Water and Sanitation Extension Engineer Africa-Kenya Health and Community Development