RCT Discussion / Frozen Excitement ratings in RCT2

Hi, I'm posting here because of a problem I'm having with RCT2, specifically with Extreme Heights. You see, recently, the excitement, intensity, and nausea ratings for all my rides has frozen in this one saved game. None of them have changed, not even for the rides I'd already built (i.e those where a new ride's track intersected with the existing ride's). This is most problematic for the new rides, since now nobody wants to ride them (i.e they show up as 'Not yet available'. This saved game is the only game which has this problem, as well as the only scenario (I've tested it with others). What should I do?

Some tidbits that may help:

-The latest ride in my park to register excitement, intensity, and nausea ratings was a Floorless Rollercoaster.

-I have built four rides since this has happened; A 4-D Rollercoaster (which was the first time I notcied this), a Stand-up Twister RC, a Hypercoaster, and a Gigacoaster.

-I have two previous saved games of the Extreme Heights scenario (I'm really impatient; the first two lasted too long), and all the rides in the second were either saved and imported, built piece-for-piece, or replaced with very similar rides in the current save file. Also, they are anmed 'Project 8' and 'Project Eight Point Five', being the first and second ones respectively.

-It is year 11 or 12 in the current park, and year 22 in Project Eight Point Five.

-I have used absolutely no trainers up to this point.

Can someone figure out what's going on with this?

A coaster can only be affected by a certain number of scenery objects/other rides/paths...There's a limit to how much the ratings can be boosted due to these items. I'm not sure what the limit is, but for the sake of an example let's say it's 100 objects...if you add 100 trees around a coaster, each one will boost the excitement a bit, but each tree after the 100th will have no effect on the ratings. 

Edit: I realize this may not answer the question...if you can't get ratings to show up on a ride, I would try demolishing and rebuilding them...if this doesn't work you may have to revert to a previous save.