Q analysis and Transmission box for Purcell factor


I am working on calculating the Purcell factor using power ratio manually without using “Purcell” in FDTD. And also looking for resonant modes and its Q factor( Vertical Q) in a photonic crystal.

I have 2 Questions while simulation.

First, I tried to calculate 3D Q factor using (high) Q Analysis in Analysis group. But after running the simulation, at the result view, “Q” of the Q analysis shows a weird graph. I attached the graph below. I don’t know what the problem is.
Also, I tried to measure 2D Q factor(Vertical Q) using Q Analysis in Analysis group same as above. This also has the same problem.

Second, I wanted to calculate the Purcell factor with Transmission box in Analysis group. I tried to use this data to calculate the Purcell factor divide by the data from Transmission box without the structure.
The graph of the transmission box, it shows negative power. the structure is a passive cavity, So I think there should be no negative power. Because negative power means power flow into the structure.

Q factor graph

transmission box

Here is my .fsp File