MaxPlugin: Some callback decorators not working for Max 6

When using Max 6 and the MaxPlugin in Field:

Integer and float lists from Max are not received by their respective _.listInt or _.listFloat callback decorator in Field. The _.listAtom decorator throws an exception when executing its container code box.

Traceback:

Max / Python threw an exception <Traceback (most recent call last):
File "", line 10, in
TypeError: 'NoneType' object is not callable

(line 10 was: @_._listAtom )

The callback decorators for _int, _float, _bang, & _doubleClick are each working on my system. These events are successfully received by Field.

I'm not sure where/how to check the Field version number. I built from source using the most recent version on February 9th, 2013.