perfcurve return one value

I used sam (spectral angle mapper) to change detection in hyperspektral image after that want to plot roc(Receiver operating characteristic) using perfcurve function but function return one value. why ? could you help me?

[Xpr,Ypr,Tpr,AUCpr] = perfcurve(hyperdata_gt,abs(result),'1'); plot(Xpr,Ypr);

[Ezgi Aslan]

[X,Y] = perfcurve(labels,scores,posclass); plot(X,Y);

labels are the true labels of the data, scores are the output scores from your classifier (before the threshold) and posclass is the positive class in your labels.