[R-sig-ME] lmer warning message

["H. Büttger"]

Hi,

I am getting these two warning message for different data when I'am 
using a lmer (R version 2.5.1):

Fehler in if (any(sd < 0)) return("'sd' slot has negative entries") : 
Fehlender Wert, wo TRUE/FALSE nötig ist

and

CHOLMOD warning: matrix not positive definite
Fehler in objective(.par, ...) : Cholmod error `matrix not positive 
definite' at file:../Supernodal/t_cholmod_super_numeric.c, line 614


Whats does it mean?


Thanks for your help!

Heike