LogixPro Elevator problem

I'm trying the elevator module in LogixPro and after downloading to the PLC when I put it in Run mode it gives the error "Stack Pointer Overflow".
I dont know if this is a Windows-generated error or a LogixPro error.
If anyone gets a chance to run this on your pc I'd like to know if you get the same error and what it means.
Thanks much

Rung 3 of subroutine 6 you try to jump to subroutine 6. This causes the stack overflow as it keeps calling it self. I assume you meant to use a return instruction instead.

Ascot,

If you correct Subroutine 6, your elevator will work (partially). The car buttons are not enabled, and it does not follow all the specifications in the Elevator Problem. It does not complete travel in one direction before reversing to go a different direction, which was one of the main specs. If it is on the way up to Floor 4, and the button on Floor 3 is pressed, it does not stop to pick up the person on 3 (as it should) but instead goes right by and the call on Floor 3 is turned off as it passes! Talk about making a bunch of waiting people mad!

Also the door never closes, so some old lady is going to get her foot caught in the crack - law suit waiting to happen.