Problem with ball game [doesn't move smoothly from one cube to another]

Hi all,
Im having problem with my ball game as whenever i make level, for example make 1 plane and then another, even that they are on the same height and position the ball doesnt move smoothly, and even if the planes are really close to each other. I have made video showing my problem [basically i have cubes as ice floor and when i move on them it doesnt move smoothly as it should and sometimes it jumps in air. Is there any way to make the movement on the cubes/objects smooth from one to another ? [i have no idea how to make it smooth, maybe some script or physics or there is something simpler to do to fix this :?
[i made video but youtube is processing it for like 15 min now]

Thanks for helping guys !

 

Anyone :?