I seem to be having difficulty building a monorail network for my park. It seems that when I have more than two stations the game won't let me put entrances or exits on any of the stations but the first. This is very frustrating as I love monorails; I can't seem to remember if I was able to do multi-station monorails in RCT3 before (it's been a few years since I last played), but I loved them in RCT1&2.

EDIT: I seem to be able to do so in sandbox mode. Could there be a limit to the length of a monorail one is able to build with multiple stations?

EDIT2: I just tested it in the park which I'm making; please see attached images below. The first is of one of the stations of the monorail I'm trying to build, which the game not letting me add an entrance to - strangely, I could add entrances/exits to the first and third stations, but not the second and fourth. The second is of a test track I made, which the game won't let me add any entrances/exits to.
I'm getting really frustrated with this. I don't know why it is working in the sandbox but then not in my park.

NB: I have RCT3 Platinum (PC CD-ROM) running on a MacBook Pro with Windows 7 installed, Intel Core 2 Duo 2.53 GHz, 4 GB of DDR3 RAM, and a Nvidia GeForce 9400M video card.

I am guessing that the terraforming of the land is uneven to place an entrance piece. Have you raised the station to see if that is the problem?

I am guessing that the terraforming of the land is uneven to place an entrance piece. Have you raised the station to see if that is the problem?

Yes, that was the first thing I tried, with no luck.