[gmx-users] grompp error

[Dinesh Pinisetty]

Hello everbody,
      I am getting following error when I am trying to do energy
minimization.
FATAL ERROR: Group protein not found in index file.Maybe you have
non-default groups in your mdp file while not using the '-n' option of
grompp.
  In that case use the '-n' option.

When I got this error I created an index file and then tried to run grompp
again using '-n' option also,still I get the same error,Could anyone tell
me where the problem is:How to sort out this problem.
Any suggestion would be gratefully appreciated.
Thanking you,
Dinesh.