lost atom using fix wall command

Hi

When i am using fix wall/lj126 command it is running in old 2009 lammps version, but when i am trying to the same script file with lammps April,2011 version it shows the error lost atoms?
Can anyone sortout what is my mistake?

Thanks
Chandan

Hi

When i am using fix wall/lj126 command it is running in old 2009 lammps
version, but when i am trying to the same script file with lammps April,2011
version it shows the error lost atoms?
Can anyone sortout what is my mistake?

with this little of information: no.
not without psychic capabilities.

axel.