Cajon Pass Bugs

I have spent the better part of three days working on a switching scenario for the Barstow Bowl (original route).
It required the player to stop at a marker of my making at the end of the scenario. I was able to play the scenario
three times before I started to add AI.Once the AI was added I could not run the scenario. I was told that the track
was blocked even thought that none of the AI were anywhere near the same track as the players train.
I removed the AI and then cleared the cashes. When I went to play the scenario again, I got the same error. Track blocked!
To be honest I am tired of the program not doing what it is told. Has anyone run into this kind of error before and what if
anything did you do to correct it.
It required the player to stop at a marker of my making at the end of the scenario. I was able to play the scenario
three times before I started to add AI.Once the AI was added I could not run the scenario. I was told that the track
was blocked even thought that none of the AI were anywhere near the same track as the players train.
I removed the AI and then cleared the cashes. When I went to play the scenario again, I got the same error. Track blocked!
To be honest I am tired of the program not doing what it is told. Has anyone run into this kind of error before and what if
anything did you do to correct it.