Error calculating moments at support?

Dear all, 

I have analyzed a 3D structure fixed to translation in x,y, z-direction and free to rotate in x,y,z-direction. Image shows that reaction moments are 0, but plotting Mz, it is possible to view Mz in point anchored to the support.

What is the problem?

I attach an image for better understanting.

Thanks.

Best,

Leonardo