[R-sig-ME] Error in asMethod(object) : matrix is not symmetric [1, 2]

[Chaudhari, Monica]

Hello All,

I am receiving this error while trying to model follow-up  restorative
costs on  patients' teeth using Gamma family mixed model. 

> lmer9<-lmer(cumappAmtCPIAdj ~ toothNo  + yrFromBase +  (yrFromBase |
ptntId/quad), data = datsample[procClass == "Restorative" & ptntId %in%
levels(ptntId)[1:10],],family = Gamma(link="log"))
The model appears to fit until you give the bellow command:
> summary(lmer9)
Error in asMethod(object) : matrix is not symmetric [1,2]

When tracing back for error, it gives:
> traceback()
15: .Call(dense_to_symmetric, from, "U", TRUE)
14: asMethod(object)
13: as(from, "symmetricMatrix")
12: .class1(object)
11: as(as(from, "symmetricMatrix"), "dMatrix")
10: .class1(object)
9: as(as(as(from, "symmetricMatrix"), "dMatrix"), "denseMatrix")
8: .class1(object)
7: as(as(as(as(from, "symmetricMatrix"), "dMatrix"), "denseMatrix"), 
       "dpoMatrix")
6: asMethod(object)
5: as(sigma(object)^2 * chol2inv(object at RX, size = object at dims["p"]), 
       "dpoMatrix")
4: vcov(object)
3: vcov(object)
2: summary(lmer9)
1: summary(lmer9)

Below is additional information about the session:
> sessionInfo()
R version 2.11.1 (2010-05-31) 
i386-pc-mingw32 

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United
States.1252    LC_MONETARY=English_United States.1252 LC_NUMERIC=C
LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base


other attached packages:
[1] lme4_0.999375-37   Matrix_0.999375-45 lattice_0.19-13   

loaded via a namespace (and not attached):
[1] grid_2.11.1   nlme_3.1-97   stats4_2.11.1

I have not had success fitting Gamma(link="log") even a single time
using lme4. It returns the above error always. Could you please point
any resolutions?

Thanks,
Monica

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