Problems in using lmer to fit a multilevel model

2008/8/20 chenlei <chenlei at ibcas.ac.cn>:

Dear??
  when I fitted my logistic model(binary data),I received an error "Error in mer_finalize(ans, verbose) : q = > n = ". what's the matter?how can I do with this problem? was this tell me the observations were not enough to fit the model ? I appreciate if anyone who use lmer could give me some advice.

Hmm.  The message was supposed to be a bit more informative in that it
should have given the values of q and n.  I will repair that.

The value of q is the total number of random effects and the value of
n is the number of observations.  I included that check because it did
not make sense to me to try to fit more random effects than you have
observations.  I guess I could be persuaded that it would make sense
in some circumstances because the random effects are determined by a
penalized least squares optimization.

What is the nature of the model that would require it to have more
random effects than observations?