[Coin-ipopt] filter: current iterate feasible; can't do restoration. Abort

[Matthew Guthaus]

I am using IPopt through the C NLPAPI. I set up a problem successfully 
and get this output after a few iterations:

ITER     ERR       MU      ||C||   ||YPY||  ||PZ||     ||D||   ALFA(V)  
  ALFA(X)     NU   #LS       F      #cor   Regu    CPU(s)
...
   14 .104E+05d .100E+00 .000E+00 .000E+00 .000E+00  .342E-02 .447E+00d 
.100E+01f .000E+00  1 0.12190353E+02  0 .000E+00 .280E+00
filter: current iterate feasible; can't do restoration. Abort
  solve_barrier: filter returns IERR =  16
  mainloop: Error: solve_barrier ends with IERR =  16

I'm not quite sure what this means... I have tried playing with my 
tolerance and scaling factors, but this doesn't change much.
The problem only has simple upper/lower bound constraints and is fairly 
smooth. It should have a minimum near 0. I have used the Matlab fmin 
function previously with good results, but with poor performance.

Any insight from the IPOpt experts?

Thanks,

Matt