Please Help! Problem in using normcdf!

hi everyone, got some problem using function normcdf here is the code,

function p_choice1 = Fechnerd(g1a1, g1a2, g1p1, g1p2, ...
                              g2a1, g2a2, g2p1, g2p2, gamma, sigma)

    mu = (g1p1.* utility(g1a1, gamma) + g1p2.* utility(g1a2, gamma)) - ...
         (g2p1.* utility(g2a1, gamma) + g2p2.* utility(g2a2, gamma));
    p_choice2 = normcdf(0, mu, sigma);
    p_choice1 = 1 - p_choice2;

function u = utility(value, gamma)
  u = abs(value).^gamma;

g*p* are for probabilities, g*a* are for outcomes. While all I got was just a vector of 1. I don't know how to solve the problem... Thank you!