ROBLOX won't load certain heightmaps

[PerilousIntent (Mantooth)]

I’ve uploaded this heightmap and I’m trying to generate it with terrain but ROBLOX won’t do it. Anyone know why?

[ImpossibleSolutions]

Is your game published or not ? If not, then you should publish it first. If yes, then the image must go through moderation before being used. Please, read this.