For a given equation say A(s)/B(s), the pole are those occurrences where the equation evaluates to Infinity, and the zeros are basically the roots of the equation.
In your case, the equation is: a(s) = s^3 + s^2 + s + 1.
Only occurrences where the equation a(s) tends to Infinity is when 's' is itself Infinite and hence MATLAB does not give you a specific pole. Zeros happen when a(s) evaluates to 0 which is the case with -1,+i,-i.
MATLAB's output are as expected. Leave a comment with your expected output.