problem in using fix depasition command

Hi dear alls,
I wnnt to use the fix deposition command to deposit some atoms as adatom at the surface,
But when i use this command

fix 1 all deposit region mobile local 2 20 1 units box
an error appears
" deosition regian expanded out of the simulation box.

I cannot understand the problem, Kindly guide me about this problem.

Muhammad Imran

The error is telling you the region into which you want to deposit
has to be contained within the simulation box. Apparently it isn't.