Spur gears not meshing>

I am making a 2-d planetary gear set in Rhino 5 but my gears don’t seem to mesh. I watched a video on how to use expressions and i typed into the keyframe editor the formula that the video showed but the gears still don’t mesh. http://www.youtube.com/watch?v=dSDWO-duseA . My large gear has 36 teeth and my small gear has 14 teeth and this is what i type into the keyframe editor for the large gear. #Object 14.Rotate X #*14/36

It’s hard to say what goes wrong without seeing the model…
Any chance you could send it to us?
You can send it to me using the following page:
We only need the two gears in the model, so if you want to you can delete the rest from the model.