Rcaller issue in parsing the strings

Question

I want to see the distinct items in the column, but I get the following error:

rcaller.exception.RCallerParseException: Variable data_item not found

The below is the code that I have used:

code.addRCode("data<-read.csv(x)");/*x is the path of the file*/
code.addRCode("data_item=unique(unlist(data$ITEM,use.names=FALSE))");
caller.setRCode(code);
caller.runAndReturnResult("data_item");
String []s=caller.getParser().getAsStringArray("data_item");