Dear List Members, I have run fslvbm steps 1 and 2 without problem. Th 4d gm mask looks good. However when I run fslvbm _ 3 _ proc, 3A seems to work but 3b returns the following error: fslvbm3b.e2091730 "ERROR: Program failed An exception has been thrown Data mask is blank. Exiting ERROR: Program failed An exception has been thrown Data mask is blank. Exiting ERROR: Program failed An exception has been thrown Data mask is blank. Exiting" Any suggestions on how to fix this problem would be greatly appreciated. Best wishes, Salil Soman, MD, MS