Problem running Heatflux example

Dear Lammps list,

I tried to run the examples provided to compute the thermal conductivity KAPPA with the Lammps distribution of 28th june 2014.

With the input script "in.heatflux" on 8 cores, I obtained a result identical to the reference provided with LAMMPS. However, if I run this input script on different on number of processors, I obtained rather different results :

1 core => Kappa= 2.85
6 cores => Kappa = 3.97
8 cores => Kappa = 3.78 (output identical to the reference provided with the Lammps distribution).
16 cores => Kappa = 4.16

I don't understand why Kappa differ when I increased the number of processors/cores. Is there any bug or misunderstanding on my part ?

Thanks for your help,