Thanks.  I used the most current version of lme4 that is why I was a bit concerned.  My data seems appropriate and with lme4 working last week on a very similar data set, I was left a bit confused.  Since I only starting implementing this technique, does anybody have some pointers on what I should look for that may potentially cause some issues?  

> 
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org] Namens Craig O'Connell
> Verzonden: maandag 28 april 2014 3:20
> Aan: r-help@r-project.org
> Onderwerp: [R] lme4 Error Help: “maxstephalfit…pwrssUpdate”
> 
> I am using a mixed model to assess the effects of various variables (i.e. treatment, density, visibility) on bee behavior (e.g., avoidance frequency - total avoidances per total visits; feeding frequency, and mating frequency).  Bee individuals is my random factor (n=63 different bees), whereas treatment type, animal density, and air visibility are my fixed factors.
> However, when I run my models, I immediately get an error that I cannot fix.  Here is a sample of my data:
> Bee   Treatment    Visits    Avoid   Feeding    Mating    Density   Visibility
> 
> 1   C   5   0   5   0      5        4
> 2   C   4   0   3   0      5        4
> 3   C   3   0   3   0      5        4
> ...
> 63
> 
> 1   PC  2   0   1   1      5        4
> 2   PC  3   0   0   3      5        4
> 3   PC  1   0   0   0      5        4
> ...
> 63
> 
> 1   M   5   0   1   3      5        4
> 2   M   3   2   0   0      5        4
> 3   M   2   0   0   2      5        4
> ...
> 63One I create my .txt file, I being my coding in R by first loading lme4.  After that, my coding starts off as follows:
> barrierdat = read.table("GLMMROW.txt", header=TRUE) barrierdat barrierdat$Visibility = as.factor(barrierdat$Visibility);
> barrierdat$Density    = as.factor(barrierdat$Density);
> 
> p01.glmer = glmer(Avoidance~offset(log(Visits))+(1|Bee),            family=poisson,
>                   data=egghead);  # null model; p02.glmer = glmer(Avoidance~offset(log(Visits))+(1|Bee)+Treatment,  family=poisson,
>                   data=egghead);
> p03.glmer = glmer(Avoidance~offset(log(Visits))+(1|Bee)+Visibility, family=poisson,
>                   data=egghead);
> p04.glmer = glmer(Avoidance~offset(log(Visits))+(1|Bee)+Density,    family=poisson,
>                   data=egghead);However, upon immediately running my models (e.g. p01.glmer), I receive the error:
> Error: (maxstephalfit) PIRLS step-halvings failed to reduce deviance in pwrssUpdate
> 
> Does anybody know what the issue is?  I ran similar data several weeks ago and had no issues.  Any Suggestions on how to proceed?
> 
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