R help - Apr 2009 - False convergence error with lmer (package lme4) - What does it mean?

Hello,

I've run 7 candidate models using mixed-effects logistic regression with 
the lmer function from the lme4 package, and I'm getting the following 
error for 5 of those models: Warning message: In mer_finalize(ans : false 
convergence (8). The candidate models all run with the same data, just 
slightly different formulas (for AIC model selection). Can anyone explain 
this error to me? 

This is the command line syntax I'm using: 
ful1 <- lmer(<dependent variable> ~ <formula> + (1 |
<effect>), data = cv,
family="binomial", na.action = na.omit)

The random intercept effect has 14 groups. 

Is there anything I can do to address this error?

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Peter Singleton
E-mail: psingleton@fs.fed.us
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