[R-sig-ME] Error message with lme

[FMH]

Dear All,

I tried to run an R scipt on a set of data with lmList function and it worked fine, but as i tried to run with lme function, the program suddently give a message error. Both script and message error are  shown below

#################################################################################
> dp <- rep(rev(1:11), 261)
> sub1 <- data.frame(sub1, dp, or)
> tmp <- groupedData(Temp ~ dp  | or, data = sub1, FUN = mean, order.groups = TRUE, labels = list(x = "Depth", y =         
    "Temperature"),  units = list(y = "(0C)"))
> lm.lis1 <- lmList(tmp)
> lm.lme1 <- lme(lm.lis1)

Error in lme.formula(fixed = Temp ~ dp, data = tmp, random = list(or = c(2.45530618001172,  : 
  nlminb problem, convergence error code = 1
  message = iteration limit reached without convergence (9)
#################################################################################

Could someone advice me the way to tackle on this problem?

Thank you
Fir