I am trying to model a planetary gear set but the sun gear is not meshing nicely with the planet gears. The module of all the gears is 1, the ring gear has 39 teeth, the planets have 12 and the sun gear has 15 teeth. I have a physical sample of this gearbox which is where I got all the sizes from, and obviously the sun gear meshes fine in reality. Is this an error with the Solidworks toolbox components or am I missing a parameter in the gear design that is causing this?

If I change the sun gear to have 16 teeth with a module of .9 the teeth line up, but the pitch diameters of the gears do not. Is this an acceptable solution or will it move the contact point of the teeth in a way that is bad for the life of the gears?