I must say I was confused as well. The blue clouds not only don't read as clouds, but they don't have any sense of scale, distance and perspective (in the sense of being a rather horizontal, vertical or other, expanse). One reason is the evenness of the texture scale.
The tree foliage texture is weird too; the tree trunk doesn't contrast enough against the bg.
Wolf's edit raised interesting points. I'd go a different way though. What I like best in your piece are the upper left corner (landscape and sky) and the lower right (character and tree trunk), but they're lost in the fog and foliage. Maybe you should get them close together and make the canvas smaller.