Hello, I would like to run a model with nesting design in lmer but I always got the error message "Matrices must have same number of columns in rbind2(..1, r)". My model is: model_3R <- lmer(N~Bareground+Habitat_type_simple+Presence+(1|Region/Ref_lmer),family "poisson") of course it doesn't say you a lot, but maybe you know about this error message. If I take the nested variable out, the model is running well. Thank you -- View this message in context: http://www.nabble.com/Problem-with-nesting-in-lmer-tp19757471p19757471.html Sent from the R help mailing list archive at Nabble.com.