FSL Error after ASL subtraction: stats/correction -mul 2 stats/correction - cannot open volume


I’ve tried to use FSL (5.0.9 and 6) FEAT to do an arterial spin labeling analysis. When I use the subtraction option in the pre-stats, during the stats analysis, I get the error:

fslmaths stats/correction -mul 2 stats/corrections

Cannot open volume stats/correction for reading!

I’ve gathered from the FSL forum that film_gls may no longer create the corrections file in the newer versions of FSL. e.g. :


Has anyone encountered this before?

Does anyone know if this error is causing incorrect outputs to be generated and what is causing the problem? Does anyone have a proposed work-around or solution?