[gmx-users] How to solve this fatal error?

[حلیمه میرسالاری]

Dear all

l am using gromacs 4.5.5 version for simulation carbon nanotubes in tip3p
water with charmm27 force feild.
I used grompp for energy minmization,but l encountered with
 fatal error:

  [ file tip3p.itp, line 40]:
Atom index (1) in settles out of bounds (1-0).
This probably means that you have inserted topology section "settles"
in a part belonging to a different molecule than you intended to.
In that case move the "settles" section to the right molecule.

Thanks a lot