some questions about bin/cylinder

Dear professor, i want to ask a question to you.Could you help me to improve the following commands?

compute 6 all chunk/atom bin/cylinder z lower 2 64.09200285 64.09200285 1 91 90 units box
fix 9 all ave/chunk 2 6 2000 6 density/number density/mass file cel.profile

the result of the commands is that there is nothing in the file of cel.profile.

Looking forward to your reply.

       Dear professor, i want to ask a question to you.Could you help me to improve the following commands?

there is not enough information and context here for a meaningful
suggestion. the most common mistake that people make is to
misinterpret the meaning of the nevery, nrepeat, and nfreq parameters.

axel.