Phase Noise Setup doesn't work in port/vsource

I'm simply simulating pss and pnoise for a port/vsource, with added phase noise "freq, noise(dBc)" pairs.

In my testbench, there's only the vsource and it's labelled output, and gnd. 

In ade, I setup pss output as voltage between vsource positive and vsource negative(gnd), no input.

But the simulation result in Direct Plot -> pnoise -> Phase Noise gives me a straight line with same value for all frequencies.

Then it means either the added Phase Noise pairs don't work, or there's sth wrong with my simulation.

Could you please tell me why?

Thank you very much.

Here's my testbench and vsource setup (when I use port, the setup is almost the same, only with a 50 Ohm impedance for the port)

Here's the ade setup for pss and pnoise:

Here's the simulation result plot of phase noise: