Taking Accelrometer Raw Data from Android

Hai I am doing working on activity recognization using smart phone. I am successfully taking values from Mobile (S5). and present in plot form. Know I want to take start point from the plot to using " Use data cursor to select the start point in the plot, key in the x coordinate (time)." and for this I use the code

      [a, t] = accellog(mobileSensor);
    fig=figure;
    plot(t, a);
    datacursormode on;
    dcm_obj = datacursormode(fig);

    startTime = input('Use data cursor to select the start point in the plot, key in the x coordinate (time).');
     dcm_obj = datacursormode(fig);
    stopTime = input('Use data cursor to select the stop point in the plot, key in the x coordinate (time).');

Now I want to take values into start time . But when I write curser on plot this do not take values .? *How I take vale in start time from Plot*?