[R-sig-ME] glmmTMB warnings and no output Gamma distribution

[Willem (Wim) Kaijser]

Hello, It was suggested to me to place my question in this mailing-list. 
I have some problems and lack of knowledge constructing a GLMM with the 
glmmTMB package (version 0.2.03). Therefore, I am sorry If the 
explanation is not as sufficient as it should be, and want to thank you 
in advance for your time.

I try to include both fixed plus random effects and correction for 
serial correlation in a GLMM with a Gamma distribution (link = 
"inverse"). However, I get several warnings and the processing time is 
long, so I prematurely stopped the permutations (see the code below). If 
the Gamma distribution, with “log” link, is used in the model containing 
only the fixed and random effects; these warnings do not occur. 
Including this with the model correcting for serial correlation it does 
return a warning, but I can extract the residuals (AIC and BIC are 
returned as NA though). This seems like the following issue: 
https://github.com/glmmTMB/glmmTMB/issues/329. However, this seems to be 
resolved. What might be the issue here (is it my coding)?

############################################################
#Code with only the fixed and random effects with warnings:#
############################################################

mod1 <- glmTMB(Chla ~ pCO2 + (1|River/ID), family = ”Gamma”, data = df)

There were 19 warnings (use warnings() to see them)
Timing stopped at: 33.7 0.08 34.19

Warning messages:
1: In nlminb(start = par, objective = fn, gradient = gr,  ... :
   NA/NaN function evaluation

#######################################################################################
#Code with both the fixed, random and correction for serial correlation 
with warnings:#
#######################################################################################

mod2 <- glmTMB(Chla ~ pCO2 + (1|River/ID) + ar1(1|Month), family = 
”Gamma”, data = df)

There were 20 warnings (use warnings() to see them)
Timing stopped at: 24.71 0.08 25.49

Warning messages:
1: In FUN(X[[i]], ...) : AR1 not meaningful with intercept
2: In nlminb(start = par, objective = fn, gradient = gr,  ... :
   NA/NaN function evaluation

Best regards,
-- 
Willem (Wim) Kaijser

Fakultät für Biologie
Aquatische Ökologie
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