Error using internal.stats.parseArgs (line 42) Wrong number of arguments

I am not able to understand the following error. Also have tried the solutions on MATHWORK question and answer. but unable to fix it.

YTest = true class labels

score1 = array of predicted scores.

MEL = positive class label

remaining {'BCC','AKIE','BKL','DF','NV','VASC'} are negative class labels.

then why is the following error???

Error using internal.stats.parseArgs (line 42)

Wrong number of arguments.

Error in perfcurve (line 324)

internal.stats.parseArgs(args,defs,varargin{:});

Error in classify_ISIC2018_Task3A_Alexnet (line 240)

[X,Y] = perfcurve(YTest,scor1{:,1},'MEL','NegClass',{'BCC','AKIE','BKL','DF','NV','VASC'});