I attach the bvecs that I'm using. The second is produced in the dmri.
You are noting that the first is in 3 rows, the second contains only 3 row with a 0
fslroi /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/dwi.nii.gz /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb.nii.gz 0 1
fslmaths /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb.nii.gz -Tmean /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb.nii.gz
bet /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb.nii.gz /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb_brain.nii.gz -m -f 0.3
mv -f /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb_brain_mask.nii.gz /Applications/freesurfer/subjects/subject_prova/Diff01/dlabel/diff
#-------------------------------------
#@# Inter-subject registration Gio 31 Gen 2013 22:40:26 CET
flirt -in /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb_brain.nii.gz -ref /usr/local/fsl/data/standard/MNI152_T1_1mm_brain.nii.gz -out /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/lowb_brain_mni.nii.gz -omat /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/xfms/diff2mni.mat -cost mutualinfo
convert_xfm -omat /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/xfms/mni2diff.mat -inverse /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/xfms/diff2mni.mat
#-------------------------------------
#@# Masks Gio 31 Gen 2013 22:41:55 CET
#-------------------------------------
#@# Tensor fit Gio 31 Gen 2013 22:41:55 CET
dtifit -k /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/dwi.nii.gz -m /Applications/freesurfer/subjects/subject_prova/Diff01/dlabel/diff/lowb_brain_mask.nii.gz -r /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/bvecs -b /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/bvals -o /Applications/freesurfer/subjects/subject_prova/Diff01/dmri/dtifit
Error: bvecs and bvals don't have the same number of entries
Darwin iMac-di-Stefano.local 12.2.1 Darwin Kernel Version 12.2.1: Thu Oct 18 12:13:47 PDT 2012; root:xnu-2050.20.9~1/RELEASE_X86_64 x86_64
trac-preproc exited with ERRORS at Gio 31 Gen 2013 22:42:02 CET