Opencv knearest neighbor

Question

I use CVKnearest Class in opencv to classify 6 classes with 10 functions as follows:

CvKNearest knn(trainData, trainClasses, Mat(), false, K ); 

then i use:

  response = knn.find_nearest(testData,K,Results,nearests,dists); 

but the results are always equal to 1, even if I give the functions of a training sample, which should give me the distance to zero and be selected as a class!

when I print Mat results like this:

 FileStorage f; f.open("result.xml", FileStorage::WRITE); f << "t" << Results; f.release(); 

He gives me a floating number,

so my question is what am i doing wrong? or how do I get the desired class labels ?!