R help - Mar 2008 - AD-model builder under R for mix logistics model, a problem.

the code is list below , i can run this code for laplace approximation 
but not importance sampling.  the code work properly if use impSamp=0 , 
but error for any other number >0 .
could you guys help me out.

thanks so much !

source("http://www.mi.uib.no/~skaug/cash/lesaffre_dat.s")
 library(glmmADMB)

 fit_glmmADMB_ip <-
glmm.admb(y~treat,random=~1,group="subject",impSamp
=100,data=lesaffre,family="binomial",link="logit",save.dir=
NULL)

Initial statistics: 2 variables; iteration 0; function evaluation 0
Function value  1.5926934e+003; maximum gradient component mag  1.2500e+001
Var   Value    Gradient   |Var   Value    Gradient   |Var   Value    
Gradient   
  1  0.0000  1.2500e+001 |  2  0.0000  6.2441e-001 |

 - final statistics:
2 variables; iteration 9; function evaluation 13
Function value  1.2593e+003; maximum gradient component mag -5.7984e-005
Exit code = 1;  converg criter  1.0000e-004
Var   Value    Gradient   |Var   Value    Gradient   |Var   Value    
Gradient   
  1-56.9607 -1.2327e-005 |  2 -3.7159 -5.7984e-005 |
 inner maxg = 9.681e-005
max separable g 9.681e-005
Newton raphson 1
 f = 971.7651636 max g = 9.245773036e-010
max separable g 9.245775812e-010
Newton raphson 2
 f = 971.7651636 max g = 2.220446049e-015
971.7651636
Error in glmm.admb(y ~ treat, random = ~1, group = "subject", impSamp
=
100,  :
  The function maximizer failed
In addition: Warning message:
In shell(paste(.path.package("glmmADMB"), "/admb/",
file_name, ".exe",  :
  'cmd' execution failed with error code 1
 >