Problem for calculating PSCF

[plastic_th]

Hello, I'm newbie for using TrajStat. I want to calculate PSCF and show it in the graph.
(Previously, I put backward trajectories data and PM data into TrajStat)
First, I created a grid box , and then I pressed “ PSCF analysis” and followed the instruction (Get Nij, Get Mij , Cal PSCF and Weight PSCF). However, the graph doesn’t show anything. What’s wrong of that?
Please Help!