weka.classifiers.trees.J48: Cannot handle string attributes!

Hi, I can't execute J48 because of this error : weka.classifiers.trees.J48: Cannot handle string attributes!

I tried to convert string attributes to nominal, without results. Could someone help me? (I'm not very expert, it's the fist time I'm using KNIME)  


If you reopen your J48 learner, you should find a column marked in red on the right of the panel, it could give you a hint on variables that give you trouble. It seems to me that J48 is a C4.5 variant, so it is made to cope with nominal values or strings. You can send me a sample of your entry data set just before the J48 learner in knime format precising the variable you want to predict. I'll check.


By the way I noticed that the 3.7 Weka / knime embedded version has some strange behaviors comparing to the previous 3.6 (proof in attachment). So give it a try.