Dear lme4-folks,

I wonder if you can help me with a query.

In our lab we are (not very advanced) users of lme4, who have until recently relied heavily on languageR. We are trying to adjust to lme4 3.0.1 and life without languageR/pvals.fnc.

As part of this process, to try to ensure continuity for our students, I recently asked our technical support to ensure that our lab machines are running the following:
R 2.15.2 with lme4 version 0.999375.42, and languageR
R 3.0.1 with lme4 version 1.0.5

I have tested the following simple bit of code under both of the above.
junk = lmer(RTlexdec ~ WordCategory + (1|Word), data=english)
This works fine under R 3.0.1 with lme4 1.0.5.

But, under R 2.15.2 with lme4 0.999375.42, I get the following error message:

"Error in validObject(.Object) :
  invalid class “mer” object: Slot L must be a monotonic LL' factorization of size dims['q']"



Do you have any idea where this problem could be originating? I'm wondering whether the versions of e.g. MASS or matrix that we have loaded, could be an issue here - might we have newer versions of these that aren't compatible with lme4 0.999375.42, or something like that?



> sessionInfo()

other attached packages:
[1] MASS_7.3-23      languageR_1.4    lme4_0.999375-42 lattice_0.20-24  Matrix_1.1-0

loaded via a namespace (and not attached):
[1] grid_2.15.2   nlme_3.1-108  stats4_2.15.2



I would be very grateful indeed for any advice as to what could be causing our problem.



Thank you very much in advance,



Rachel Smith (University of Glasgow)







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