Estimated G Matrix not positive definite getting "." for the std error of some vars in the random statement getting this error and not sure why Some reasons I've been told 1 scaling of vars ran proc means and all vars are close to the same scale 2 vars could be linear combination of each other ran model with proc reg and the highest VIF is about 2.3 3 model contains binary vars of 4 binary vars only one is giving the "." error

running model with 100 classes 30 vars and about 100 obs per class get the error ran the same model with only 12 classes get all vars to randomize

please any help is greatly appreciated