Sprite superposition in 2D paper

Hi,

I’m have some trouble to understand the sprite superposition in the sidescroller 2D.

This happen not always, but very often. If my main game plan is on “x” = 0, and if i want to put a tree in the background (so the player will show in front of the tree) i will choose for exemple “x= -100” for the tree, and i want to put a flower in "x = +100) in front of the tree. But even like this, sometimes when i click play, the flower sprite appear behind the tree…

I really don’t know why, sometimes it works, and sometimes not ! Maybe in sprites parameters ?
Thanks a lot for help !

It’s really crazy…

I can take the same two sprites, and i will have different result by doing the same things…
I’m really lost.