region command with block &union argument

Dear Users,

I wanna dump the atoms in specified region.The total number of dumped atoms can be change with radius R.However,the total number of dumped atoms can not be changed with the lateral size of plate.
Like, If I change R=10 to R=20.The dumped atoms will be decreased. If I change the plate lateral size X=40 to X=60 and Y=40 to Y=60,the total number of dumped atoms can not be change.

Is there any one knows what’s wrong with my specified region shown below.Any suggestions are

partial input :

region sideplate block 0 40 0 40 0 30 side in
region sidetip sphere 20 20 30 10® side out
region myregion union 2 sideplate sidetip

Thank you very much

Best Regards

Liyi Bai

I do not see a particular problem in the command you copied here.
Could you post the part of your parameter and log that describes the
construction of the system, regions and groups?