From the Help files – Deformer Object:
“The deformer will affect its parent object and the hierarchy below that parent. This means that a deformer will affect any object at its level in the hierarchy (since those objects are children of the deformer’s parent) and any object below the deformer’s level in the hierarchy (since those objects are in the hierarchy of the deformer’s parent). However, a deformer will have no affect if it is positioned at the top level of the Object Manager hierarchy, since it will have no parent.”
Assuming that you want to rotate the platter and mat together, simply place them all in a null as shown below, and rotate the null.

or
