Well, the good news is that I get it to work after redid my calibration. Now I can use it to tell me what filtration I should set and the exposure as well. It works for several negatives and two kinds of color papers I used so far.
So now for each session, I replenish my chemicals. Then use a test strip to calibrate the developer. The difference is normally small since my developer is stable now. Then for each negative, I use the probe to meter up to 8 areas of the frame, and I can control where I want it metered. Then I would use the color filters to balance out the star and set the aperture to get the exposure time I want. After that I just need to print one or two test prints (about 4x5 size, or even 2x5 size) to verify the settings. I normally print 8x10 and larger.
Compared with the Beseler PM2, it is a huge improvement. With the grey calibration, I do not have to have a "perfect" print. The auto balancing is great. The best thing for the colorstar is that you balance all three colors at the same time and this is really fast. And you can test chemical change with one single test strip, a 1"x5" paper.