Can You Help Me with this error

Error using classreg.learning.FullClassificationRegressionModel.prepareDataCR (line 231)

X and Y do not have the same number of observations.

Error in classreg.learning.classif.FullClassificationModel.prepareData (line 501)

classreg.learning.FullClassificationRegressionModel.prepareDataCR(...

Error in classreg.learning.FitTemplate/fit (line 218)

this.PrepareData(X,Y,this.BaseFitObjectArgs{:});

Error in ClassificationECOC.fit (line 116)

this = fit(temp,X,Y);

Error in fitcecoc (line 356)

obj = ClassificationECOC.fit(X,Y,ecocArgs{:});

Error in leavesTrain2 (line 291)

svm=fitcecoc(trainPC,grouping);