Undefined variable "dspdata" or class "dspdata.psd

I'm trying to run the matlab sample problem below (<http://www.mathworks.com/help/signal/ref/dspdata.psd.html?searchHighlight=psd)>, but am getting the undefined variable 'dspdata' or class 'dspdata.psd' error. This is in 2013b and I have the statistics tool box installed per check using the 'ver' command.

Fs = 32e3; t = 0:1/Fs:2.96; x = cos(2*pi*t*1.24e3)+ cos(2*pi*t*10e3)+ randn(size(t)); nfft = 2^nextpow2(length(x)); Pxx = abs(fft(x,nfft)).^2/length(x)/Fs;

% Create a single-sided spectrum Hpsd = dspdata.psd(Pxx(1:length(Pxx)/2),'Fs',Fs); plot(Hpsd); Undefined variable "dspdata" or class "dspdata.psd".