title: Caret train method complains Something is wrong; all the RMSE metric values are missing
body: <p>On numerous occasions I've been getting this error when trying to fit a <code>gbm</code> or <code>rpart</code> model. Finally I was able to reproduce it consistently using publicly available data. I have noticed that this error happens when using CV (or repeated cv). When I don't use any fit control I don't get this error. Can some shed some light one why I keep getting error consistently.</p>
  <pre><code>fitControl= trainControl(&quot;repeatedcv&quot;, repeats=5)
  ds = read.csv(&quot;http://www.math.smith.edu/r/data/help.csv&quot;)
  ds$sub = as.factor(ds$substance)
  rpartFit1 &lt;- train(homeless ~ female + i1 + sub + sexrisk + mcs + pcs, 
                     tcControl=fitControl, 
                     method = &quot;rpart&quot;, 
                     data=ds)
  </code></pre>