title: Error "'what' must be a character string or a function" using lme4::glmer in R
body: <p>I got the following error message even using the example from lme4::glmer:</p>
  
  <pre><code>&gt;require(lme4)
  &gt; (gm1 &lt;- glmer(cbind(incidence, size - incidence) ~ period + (1 | herd),
  +               data = cbpp, family = binomial))
  Error in do.call(new, c(list(Class = "glmResp", family = family), ll[setdiff(names(ll),  : 
    'what' must be a character string or a function
  </code></pre>
  
  <p>I hunted around and can't figure out what's wrong. Does anybody have some idea?</p>