found one problem with the queries. I will let you know once its fixed.
Switch([A] * [B}>0 And [A] * [B}<5,"Green",[A] * [B}>4 And [A] * [B}<13,"Yellow",[A] * [B}>12,"Red",True,"ExistingControls ")
This 'True' bit was assigning a default value. So this was removed and replaced with [A]*[B] = 0