python 2.7 - Why won't my nltk classification model persist with joblib? -

i've noticed others have had problems on different operating systems , i've heard there may within module disallows loading persistent classification model. i'm using mac python 2.7 , enthought canopy's editor.

this i'm using export , appears work:

joblib.dump(classifier, 'nbv1.pkl') 

and i'm using import via shell:

joblib.load('nbv1.pkl') 

this error get:

attributeerror: 'freqdist' object has no attribute '_n'

i'm assuming means model not exporting properly. have not been able automate export process within program , must shell.

thank advice.

i believe due compatibility issue nltk classifiers.