I have encountered this error a couple of times when re-running stats and post-stats. This occurs during the stats portion on the constrasts comparing the 2 EVs. usr/local/fsl40/bin/fslstats thresh_zstat2 -l 0.0001 -R ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image 0.000000 0.000000 /usr/local/fsl40/bin/fslstats thresh_zstat4 -l 0.0001 -R ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image ERROR:: Empty mask image 0.000000 0.000000 So, obviously the are no activation clusters in the resulting files. Thanks in advance.