After running a group comparison using qdec I wanted to use mc-z for multiple comparison correction I tried running:

mri_glmfit-sim \ --glmdir MTA_ADHD_MJ2 \ --sim mc-z 1000 2.0 mc-z.negative \ --sim-sign abs --cwpvalthresh 0.999 \ --overwrite

ERROR: dimension mismatch between X and contrast MTA_ADHD_MJ2/tmp.mri_glmfit-sim-9440/lh-Avg-thickness-Age-Cor.mtx X has 4 cols, C has 8 cols

What does this mean and how to fix it?