SVM classification for healthy a

segmented_features=sFeat;

%Feature reduction using PCA

[coeff,G,latent]=pca(segmented_features); %score==G mxn

%traindata

xdata=G(1:60,:);

group_label=label(1:60,:);

group_label=double(group_label);

%testdata

xtdata=G(61:100,:);

groupt_label=double(label(61:100,:));

%SVM

svmStruct1 = svmtrain(xdata,group_label);

species = svmclassify(svmStruct1,xtdata);

Why in this code my SVM does not work and I have these errors:

Reference to non-existent field 'SupportVectors'.

Error in svmclassify (line 60)

if size(sample,2)~=size(svmStruct.SupportVectors,2)

Error in Both3march (line 17)

species = svmclassify(svmStruct1,xtdata);

when I check the svmStruct1= number of classes are recognised 60 instead of 2! can any one help me.