title: C50 via caret package struggling
body: <p>I'm struggling with caret train wrapper for C50 package. I'm trying to fit a predictive model 
  with </p>
  
  <pre><code>train(x=dataTrain[,predModelFactorized], y=dataTrain[,outcome], method="C50", metric="ROC", trControl=trCtrl,   tuneGrid = c50Grid)
  </code></pre>
  
  <p>with </p>
  
  <pre><code> c50Grid &lt;- expand.grid(trials = c(1:9, (1:10)*10),model = c("tree", "rules"),winnow = c(TRUE, FALSE))
  </code></pre>
  
  <p>I get </p>
  
  <pre><code>Error in train.default(x = dataTrain[, predModelFactorized], y = dataTrain[,  : 
    wrong model type for classification
  </code></pre>
  
  <p>and my session info is </p>
  
  <pre><code> sessionInfo()
  R version 3.0.2 (2013-09-25)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  
  locale:
  [1] LC_COLLATE=Italian_Italy.1252  LC_CTYPE=Italian_Italy.1252   
  [3] LC_MONETARY=Italian_Italy.1252 LC_NUMERIC=C                  
  [5] LC_TIME=Italian_Italy.1252    
  
  attached base packages:
  [1] splines   grid      stats     graphics  grDevices utils     datasets 
  [8] methods   base     
  
  other attached packages:
  [1] pROC_1.7.1      nnet_7.3-8      Formula_1.1-1   survival_2.37-7
  [5] caret_6.0-24    ggplot2_0.9.3.1 lattice_0.20-29 rj_1.1.3-1     
  
  loaded via a namespace (and not attached):
   [1] car_2.0-19          cluster_1.15.2      codetools_0.2-8    
   [4] colorspace_1.2-4    compiler_3.0.2      dichromat_2.0-0    
   [7] digest_0.6.4        foreach_1.4.1       gtable_0.1.2       
  [10] Hmisc_3.14-3        iterators_1.0.6     labeling_0.2       
  [13] latticeExtra_0.6-26 MASS_7.3-31         munsell_0.4.2      
  [16] plyr_1.8.1          proto_0.3-10        RColorBrewer_1.0-5 
  [19] Rcpp_0.11.1         reshape2_1.2.2      rj.gd_1.1.3-1      
  [22] scales_0.2.3        stringr_0.6.2       tools_3.0.2   
  </code></pre>
  
  <p>Thanks in advance</p>