I don't know what your data look like, but I recently ran into this error message while using Anova() in the {car} package, and I resolved in by replacing the categorical predictors in my model with orthogonal contrasts. I did something along these lines:
fac <- factor(c("M","F","M","M","F")) # A categorical predictor. contrasts(fac) # Default numerical values used by Anova(), anova(), lm(), aov(), etc. contrasts(fac) <- "contr.sum" # Orthogonal contrasts to apply to "fac". facCont <- contrasts(fac)[fac] # Assign values in new variable. Replace "fac" with "facCont" in model. Of course, this may have nothing to do with the reason your model was misbehaving. -- View this message in context: http://r.789695.n4.nabble.com/about-error-while-using-anova-function-tp4159463p4353590.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.