Edge Detection for Coursera

Im trying to finish my "Mastering Programming for Matlab" on coursera, but im stuck on this question

Here are my code

function edg = edgy(pict)

test = double(pict);
sx = [-1 0 1; -2 0 2; -1 0 1];
sy = [ 1 2 1; 0 0 0; -1 -2 -1];
edg = zeros((size(test,1)-2),(size(test,2)-2));

for ii = 2:(size(test,1)-1)
    for jj = 2:(size(test,2)-1)
        A = test((ii-1):(ii+1),(jj-1):(jj+1));
        x = sx.*A;
        x_sum = sum(sum(x));
        y = sy.*A;
        y_sum = sum(sum(y));
        M = sqrt(x_sum^2 + y_sum^2);
        edg(ii,jj) = M;
    end
end
edg = uint8(edg(1:end-1, 1:end-1));

end

And this is my output

But this is what i get when i submit it

What should i do? I have no clue ._.

[AMAL SASI]

function edg = edgy(pict)
test = double(pict);
size(pict)
sx = [-1 0 1; -2 0 2; -1 0 1];
sy = [ 1 2 1; 0 0 0; -1 -2 -1];
edg = zeros((size(test,1)-2),(size(test,2)-2));
for ii = 2:(size(test,1)-1)
    for jj = 2:(size(test,2)-1)
        A = test((ii-1):(ii+1),(jj-1):(jj+1));
        x = sx.*A;
        x_sum = sum(sum(x));
        y = sy.*A;
        y_sum = sum(sum(y));
        M = sqrt(x_sum^2 + y_sum^2);
        edg(ii-1,jj-1) = M;
    end
end
edg = uint8(edg);
end