[gmx-users] centre of the system: error

[minnale]

Hi all, 
I am trying to make centre of the bilayer so I used following command line
trjconv -f 20nspopc.xtc -centre rect -o 20nstrjout.xtc -n water.ndx based on http://www.gromacs.org/pipermail/gmx-users/2003-June/005995.html
here I selected 3 (solution) again 3 (solution) for output of the selecting group
this command ran fine
when I feed 20nstrjout.xtc to g_density 
g_density -f 20nstrjout.xtc -s em.tpr -d z -o waterden -n water.ndx
Group     0 (      System) has 14036 elements
Group     1 (        POPC) has  6656 elements
Group     2 (         SOL) has  7380 elements
Group     3 (         SOL) has  7380 elements
Select a group: 3
Selected 3: 'SOL'
Reading frame       0 time    0.000   Segmentation fault

where is the mistake happening? 

Could anyone tell me

Thanks in advance
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20081112/ba31ea21/attachment.html>