HB simulation of two input signal

Hello, in the following circuit shown bellow i have two type of inputs and the output supposed to be the harmonics of a differential signal between the nodes of the capacitor as shown bellow.

i tried to simulate a two tone 10G and 10.1G to indicate that we have two inputs but its not working ,as shown in the end bellow?

where did i go wrong? and how to extract the hamonics of a differential signal shown bellow?

Thanks