[R] a warning message from lmer

[Lan Wei]

Hi all,

I have a problem when running lmer.
In my data set, Agree is a binary(0/1) response. WalkerID and ObsID is
the identification number of the subjects. the description of the
other variables are as follows:
> levels(regdat$Display)
[1] "Dynamic" "Static"
> levels(regdat$Survey)
[1] "HM1_A" "HM1_B" "HM1_C" "HM2_A" "HM2_B" "HM2_C" "ST_A"  "ST_B"
"ST_C"
> levels(regdat$Emotion)
[1] "aneu" "ang"  "con"  "joy"  "joy " "sad"
> levels(regdat$ObsGender)
[1] "F" "M"
> levels(regdat$WalkerGender)
[1] "F" "M"

the watning is:
>
fit1<-lmer(Agree~Display+Survey+Emotion+WalkerGender+ObsGender+(1|WalkerID)+(1|ObsID),family=binomial(link='logit'),data=regdat)
Warning message:
In mer_finalize(ans, verbose) : gr cannot be computed at initial par
(65)

Does anybody have some hint to solve this problem? I'd very much  
appreciate it!

Thanks,
Lan Wei