Dear Alfonso,

Thanks for looking into it. I have noticed that the WARNING sign appears only when I choose covariates like age or cognitive scores (continuous values). It does not appear when I choose these covariates in combination with subject groups hence I only took screen shot for age covariate. Please find the screen shot attached, it doesn't offer any WARNING description though despite showing WARNING instead of showing n=X. Could it be because I have n=63 in the pipeline and the covariate has 63 entries but with a zero entry for one subject which I want to discard due to quality control failure? Then again when I do add non-zero value for that one subject, the WARNING is still there.

Any thoughts on second part of my query (difference in results)?

Kind regards,
Dilip