How to set the right PME parameters for amber's prmtop and inpcrd files?

From: a a (
Date: Wed Jan 26 2011 - 04:17:32 CST

Dear Sir/Madam,
I have prepared the prmtop and inpcrd with xleap in AMBER10.
In xleap, start with a water-free pdb file, I have prepared xxx_vac.prmtop and xxx_vac.inpcrd.
After adding Na+ and water molecules, with the "addion" and "TIP3BOX 8.0" commands. I have prepared xxx_wat.prmtop and xxx_wat.inpcrd.
I have two questions here, as I want to do the analysis with NAMD
(1) For the parmfile and ambercoor input lines of NAMD, should I use xxx_vac files or xxx_wat files obtained above?
Is NAMD will not read the Na and water molecules in these files, even if I used xxx_wat.prmtop and xxx_wat.inpcrd files?
Can I keep using the boundary/ water molecules's geometries obtained in AMBER for NAMD calculations?
(2) If new boundary parameters need to be set, how can set it up? i started with the xxx_vac files (the molecules is about 70x70x70 A in size, before adding Na and water in AMBER10). I have send the PME section as follows: I read the cellorigin from the centroid of xxx.pdb file in pdb viewer. So, I set boundary with 100A, with a aim to cover all the atoms in the pdb file.
PME on
PMETolerance 1e-06
PMEGridSpacing 1
cellBasisVector1 100.0000000 0.0000000 0.0000000
cellBasisVector2 0.0000000 100.000000 0.0000000
cellBasisVector3 0.0000000 0.0000000 100.0000000
cellOrigin 22.045 0.7493 30.7129
PMEGridSpacing 1.5
wrapAll on

However, the following errors appear.
ERROR: Constraint failure in RATTLE algorithm for atom 9999!
ERROR: Constraint failure; simulation has become unstable.

I tried to increase the cellBasisVector from 100. to 500. The same error message appears. while atom 9999 is one of the surface atom in the molecule.
I double checked the geometries of the xxx_vac.prmtop and xxx_vac.inpcrd files, they are alright, as when I run xxx_wat.prmtop and xxx_wat.inpcrd files in AMBER10. No error message indicating bad geometries appears. So, i suspect I have done something wrong in the NAMD input file or boundary setting, could you mind to give me some hints what may goes wrong?
Best regards,

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