Thrillville of the rails..

[chancherie]

Got this game the other day and everythings great , love everything about it except i HATE then thing now lol as one of the challenges is to build a whoa coaster with atleast 2 WHOA sections , so i did one with atleast 2 that didn't work so i did about four and neither did that , so anybody any idea on what i have to do please?