you shouldn't be using x=290 for that would only be true if the character is exactly at x=290
Even at x=290.5 or x=291 or 289 nothing will happen..
the platform is most likely wider than 1 pixel so that wont work..
maybe using a condition in which you reference this specific platform or is overlapping at offset would work, but that all depends on how you have your layout and events set up..