an error coming across the R script

[wanggui1201]

for (i in 1:27){

• mycontrols = ctree_control(mincriterion = tunegrid[i,1],

•                              minbucket = tunegrid[i,2], 
  

•   		 maxsurrogate = tunegrid[1,3])      #is there any problem with [1,3] ?  or [i, 3]
  

• tree.list[[i]] = ctree(formula, data = train, control = mycontrols)
• }
  Error in .y2infl(mfyx, response = d$variables$y, ytrafo = ytrafo) :
  unknown response class