Derailment issue

[RonKStevens]

I am creating a scenario where the driver engine is on a side track, and must switch on to the main line after an AI train passes headed the opposite direction.
Once the AI train passes, I can either proceed forward through an interlocking to get on the main, or reverse through an interlocking to get on the main. My driver engine will be headed in reverse following the AI train that just passed. I have two problems:
If I go forward on to the main, the entire program crashes (locks up) when the driver locomotive gets through the interlocking
If I go in reverse, the path diagram at the bottom of the screen properly changes showing the station stop on the main (which is where I want to go). But when I go through the interlocking the train derails and ends the program. Why is it derailing if the path is showing properly?
The issue happens not at the first switch, but at the second switch which is on the main line.
Both choices do not permit the manual operation of those switches, so the user cannot wait for the train to pass, then throw the switch, and then proceed.

Any help would be great. Thanks.