IOA dragon trainer!!!!

I just started using it right, but i already had a beautiful masterpiece going without it. well a few days ago i tried to create more vehicles for the monorail, and it messed EVERYTHING up. Now if i close a ride down and try to reopen it, it says "Cannot create enough vehicles"!! I am pissed! Has anyone ever had this problem and can anyone help me with it? Im going crazy here

do you have a lot of rides?

yea something like 150. the park is 52 years old and i dont feel like losing it over some stupid trainer.

i think you can only have like 5000? sprites or something at one time
try turning off some other rides (double-click so the cars disappear from the track) then open the other ride again