svm not showing figure for 3 dimensional data.

I want to svm with 3 dimensional data i.e. n*3, but figure not showing for 3 dimensional data. I am using

svmStruct = svmtrain(svmtr,label,'kernel_function','rbf','ShowPlot',true)

its showing error as follows:

Warning: The display option can only plot 2D training data. 
> In svmtrain (line 403)

so svm plot for 3 dimensional data not possible.