[R] nlminb failed to converge with lmer

[Jérôme Lemaître]

Dear all,

I'm building binomial mixed-model using lme4 package. 
I'm able to obtain outputs properly except when I include two particular
variables: date (from 23 to 34; 1 being to first sampling day) and Latitude
(UTM/100 000, from 55.42 to 56.53). No "NA" is any of those variables.
In those cases, I get the warning message: "nlminb failed to converge"
I tried to modify lmer controls as : msMaxIter; maxIter... but I still get
the message.
Should I bother about it?
If yes, what should I do to not get the message?

Thank you all in advance for you answers.

PS: My model writing is for example

Fm<-lmer(alive~factor(sex)+mass+parasite+Latitude+(1|ID), family=binomial,
method="AGQ", data=donnee).

Where "parasite" is presence/absence (0 or 1) and ID is the station identity
where I captured 0 to 20 specimens, each being alive or dead, having a sex,
a mass, a presence/absence of parasite. Latitude is given at the station
level. Date is given at the specimen level because I sampled for 4 days in
each station.


Jérôme Lemaître
Ph.D. student
Départment of biology,
University Laval
Quebec, Canada