Why i can't paint 3 materials on landscape ?

There is 3 materials,
Snow-Main paint which is applied to everywhere
DirtySnow and RockSnow.
So when i try mix RockSnow and DirtySnow on one landscape part it turns as u see gray default material.Can someone help me what is goin on?

UP UP UP! Still need help.

Just change your textures to Shared Wrap.

aah how ? Would you explain ? Edit: found it ! Sampler Source-Shared Wrap.

god d*** it worked.Do you know that you are a life saver? Thanks!