i want segmentation using "imsegfmm"

i want segmentation using "imsegfmm" but it gives an error. i am not expert in matlab plese help me following is code:-

I = imread('yellow.jpg'); imshow(I); title('Original Image') mask = false(size(I)); mask(170,70) = true; W = graydiffweight(I, mask, 'GrayDifferenceCutoff', 25); thresh = 0.01; [BW, D] = imsegfmm(W, mask, thresh); figure,imshow(BW); title('Segmented Image')

figure,imshow(D); title('Geodesic Distances');