CST helices Simulation

Hello,
I made a helical 4-elements array design..I got a very good value of gain. But, unfortunately when I made a Hexagonal 6-elements array a null presented in the radiation pattern, beside bad gain and very wide beam width...
can any one help me in finding a solution for this problem please????
I'm using waveguid ports.
I would really appreciate it if anyone can help me :)

thanks