[Freesurfer] error recon-all

Hi All, I have a problem. I run recon-all on f-MRI of a group of children (3-12 years). In some of them I have this error in recon-all

imgrege: no voxels in register ERROR: 'imgreg_4dfp /opt/freesurfer/average/711-2C_as_mni_average_305 /opt/freesurfer/average/711-2B_as_mni_average_305_mask talsrcimg_g11 none talsrcimg_to_711-2C_as_mni_average_305_t4 1283' failed! status=254 ERROR: mpr2mni305 execution aborted ERROR: mpr2mni305 failed, see transforms/talairach_avi.log Linux node6 2.6.18-5-amd64 #1 SMP Tue Oct 2 20:37:02 UTC 2007 x86_64 GNU/Linux

recon-all exited with ERRORS at Wed May 13 18:48:05 CEST 2009

Do you know what this problem is? Which is the origin of this problem? Do you konw how to fix it? thanks, Anita di Iasio