[Pw_forum] charge is wrong

[sezginaydin at gazi.edu.tr]

Dear PWScf users,
I work on the PtN Rocksalt structure. My input file for pw.x as foolowing:
-------------------------------
PtN
2 atoms, NaCl bulk
&control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='PtN'
    pseudo_dir = '/home/sezgin/espresso-4.0.1/pseudo',
    outdir='./'
/
&system
    ibrav = 2, 
    celldm(1) = 4.4
    nat= 2, 
    ntyp= 2,
    ecutwfc = 20
/
&electrons
    conv_thr = 1.0e-8
    mixing_beta = 0.7
    mixing_mode = 'plain'
/
ATOMIC_SPECIES
 N  14.0 N.pw91-van_ak.UPF 
 Pt 190.0 Pt.pw91-n-van.UPF
ATOMIC_POSITIONS
 N 0.00 0.00 0.00 
 Pt 0.5 0.5 0.5 
K_POINTS {automatic}
3 3 3 0 0 0
-----------------------------

when i work pw.x, i get the error:

WARNING: integrated charge=    14.30000000, expected=    15.00000000

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     from electrons : error #         1
     charge is wrong
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     stopping ...

what is the problem?
thanks for your interest