title: R: lme, cannot evaluate groups for desired levels on 'newdata'
body: <p>I'm running an <code>lme</code> -model from the package <code>nlme</code> on R v.3.0.2.
  I'm trying to extract the model estimates with <code>predict.lme</code>, but it returns an error. Here's the code to replicate the error:</p>
  
  <pre><code>my.model = lme(fixed = Maxi ~ Time*Origin, random = ~ 1 |Genotype, method = "REML", weights=varPower(), data=dd)
  new.my.model &lt;-  data.frame(Origin = c("Ka", "Ka", "La", "La"), Time = c("mor", "eve", "mor", "eve"))
  predict(my.model, new.my.model, level = 0:1)
  #Error in predict.lme(my.model, new.my.model, level = 0:1) : 
  #cannot evaluate groups for desired levels on 'newdata'
  </code></pre>
  
  <p>and here's the data:</p>
  
  <pre><code>dd&lt;-read.table(text="Origin Genotype  Time Maxi
  Ka    Ka1     mor 14,59
  Ka    Ka1     eve 13,42
  Ka    Ka11    mor 14,08
  Ka    Ka11    eve 16,29
  Ka    Ka15    mor 14,38
  Ka    Ka15    eve 14,56
  La    La1     mor 17,82
  La    La1     eve 13,28
  Ka    Ka1     mor 16,44
  Ka    Ka1     eve 15,52
  Ka    Ka15    mor 13,76
  Ka    Ka15    eve 13,55
  Ka    Ka1     mor 19,15
  Ka    Ka1     eve 19,12
  La    La6     mor 10,54
  La    La6     mor 11,38
  La    La6     eve 10,48
  Ka    Ka15    mor 15,25
  Ka    Ka15    eve 16,51
  La    La1     mor 17,46
  La    La1     eve 15,57
  Ka    Ka1     mor 16,83
  Ka    Ka1     eve 15,63
  Ka    Ka15    mor 14,54
  Ka    Ka15    eve 15,09
  La    La1     mor 11,3
  La    La1     eve 11,94", header=TRUE, dec=",")
  </code></pre>
  
  <p>Data is two factors (Ka, La) with two levels each (mor, eve) and a random effect. I'm trying to extract the estimates for the 4 levels of data, i.e. Ka,mor ; Ka,eve ; La,mor ; La,eve.</p>
  
  <p>First asked over at CV in another context, but I was recommended here.</p>