Error in MEEM(object, conLin, control$niterEM) : Singularity in backsolve at level 0, block 1 in LME model

Hi,
I hope someone can help me. I'm using nlme to fit models.

My dataframe (1785 obs) :
$ id: Factor w/595 levels
$ treatment: Factor w/3 levels
$ provenance: Factor w/16 levels
$ repetition: Factor w/4 levels
$ bloc: Factor w/66 levels # nested to repetition
$ response: num ... (1777 obs and 8 NA) # 3 repeated measures by id
$ status: Factor w/3 levels, "dominant","codominant","suppressed" # there
are 6 provenances without suppressed trees

I want to run a modele like this :

modele <- lme(response  ~ provenance + treatment + provenance:treatment +
status + status:treatment + statuts:provenance,
                   random = ~ 1|repetition/bloc,
                   correlation = corAR1(form = ~ 1|repetition/bloc/id),
                   data, method= "ML", na.action =na.omit)

I get the message :
Error in MEEM(object, conLin, control$niterEM) :   Singularity in backsolve
at level 0, block 1 in LME model

If I run the modele without the interaction statuts:provenance, it works.

Can anyone tell me how to resolve this error ?

Thanks,
Arivoara Rabarijaona

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