CST-Parallel symmetry planes

When I tried to run my simulation, the CST give me error that there are parallel symmetry planes and the farfield can't be processed.
Anybody knows what is the problem?

U need to use open ad space in the boundary condition. In your case the boundary is touching one of the metal surface
^.^

I already used open ad space in the direction of propagation, and perfect conductor at the top and bottom of the structure as a boundary condition. and I don't have metal in my design.

For farfield, u need to use add space in all directions. If is not metal it can be any surface e.g. substrate

Otherwise u upload ur model file

I have added space in all directions and it works,
Thank you for your help

Actually CST requires symmetical boundary in all palne for calculating stable radiation pattern.