Rotate an object with makehgtform - zrotate only around the origin

Hey everyone,

I'm trying to use a slider and rotate a sphere. It works if the sphere is in the origin. but my sphere is at point (2.5,2.5,7.5) when I rotate it, the entire sphere rotates still around the origin. I want it to stay in the point and just spin.

My code: this is my slider function

function  slider_callback1(hObject, eventdata)

            s1 = get(slider, 'value');        
            R1 = makehgtform('zrotate', s1);
            set(t1, 'Matrix', R1);
            drawnow;
  end

Where

t1 = hgtransform;
set(sphere_1, 'Parent', t1);