Contact Problem example

Hello I attached two file the first test1 is going well, the second one test5 is stopped.
The problem is a contact problem.
In the first one I impose a displacement in uy direction and in second one the force in y direction.
When I apply as dof a force and not a displacement the solution see zero pivot.
I insert olso beam to stabilize the solution but the analisys don't run, there is someone can solve the problem and expalne me?

Regards
Jacopo