I am having problems using the /lme /command to fit mixed models. I have 
a data set similar to longitudinal data, except the hypothesised 
correlation is between observations taken from different individuals in 
the same family rather than from the same individual at different times. 
As soon as I try to specify any correlation structure other than 
independent, I get the error message "/Error in x$formula : object of 
type 'closure' is not subsettable/". Have you any idea what /R /is 
objecting to and how I might fix it, and if not, can you suggest h
any other way I can get R to fit a linear mixed model? The data set is 
VERY unbalanced with almost 2/3 of the "families" being single 
individuals, so maybe /R/ doesn't like being told to find correlation in 
univariate data subsets. ANY advice is welcome!

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