try checking the skill
try checking the skill. when you go to the building missions menu, highlight the required mission, and it will say something in the bottom like this (for example):
Build a Dune Buggie race track with the required skill:
60 skill 70 skill 80 skill
$100 $200 $300
build your track. once your finished, there will be a small box saying the skill and thrill of your creation. if the skill of you track meets the the required amount of skill, then your good to go. hope this helped!
(p.s if you want lots of skill, try making the track
very high then make some drops)
(also, theres a cheat at this website:
http://www.ign.com/cheats/games/thrillville-off-the-rails-wii-904622. check it out!