Using Gaussian Mixture Model (fitgmdist) to test clustering of three variables

I am trying to use Gaussian Mixture Model to cluster data based on three different variables. I know it is possible to cluster data using GMM for three variables in R, but I am trying to do this in MATLAB. So, is it possible to cluster using GMM and fitgmdist using three variables?

I have tried just entering a matrix of three variables into the data of fitgmdist and it just takes the first two variables, so I am thinking it is not possible using MATLAB.

[Adam]

The help says that each column represents a variable so I don't see why it wouldn't work. It is a while since I actually used the GMM code in Matlab though so I can't remember off-hand how I set mine up. I had 3 variables by default though because I was clustering on an RGB image.