[ADMB Users] Function Maximizer Failed in glmmADMB using Beta Distribution

[Andrew Harbicht]

Hello ADMB community,

I am relatively new to modelling, especially with ADMB and I am currently trying to run a series of glmm on data using the beta distribution. The response variable are genetic admixture in fish and is measured as a proportion, the fixed variables are continuous environmental parameters and the random variable is the lake (17  different lakes) in which sampled fish came from.
I created several models with a single fixed variable each using the following syntax:

glmm15<-glmmadmb(formula = Admix ~ StMonth + (1|Lake), data = data, family = "beta")

 and they seem to work fine, however several parameters result in the following error:

Error in glmmadmb(formula = Admix ~ StMonth + (1 | Lake), data = data,  : 
  The function maximizer failed
In addition: Warning message:
running command './glmmadmb -maxfn 500 -noinit -shess' had status 1

I've tried running this with verbose=T and the message "matrix not pos definite in sparse choleski" appears in red within the analysis and just before the model finishes running there is the message "Hessian does not appear to be positive definite"

I am currently using a mac running os X 10.6.8 with the most recent version of R (2.14.0) and the glmmADMB package which was available on December 9th 2011. 

I would greatly appreciate any advice or suggestions people may be able to provide regarding this problem.
I've attached a smaller version of my database with the random variable, response variable and three fixed parameters, one which seems to work (pH) and two which return error messages or warnings (SDI and StMonth)
I've also attached a test file with sample r codes.

Sincerely,

Andrew Harbicht
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