Pydoc Locate Method Finds Class, but the Methods Are Not There?

I have a base class called customclass that dynamically loads a 2nd class and calls methods on it. I use the 2nd answer here: How to dynamically load a Python class to implement this, the method that dynamically loads the 2nd class in my customclass follows:

def executedf2in(self, dfin1, dfin2):
    custom_class = locate(self.custom_class_name)
    dfresult = custom_class.df2in(dfin1, dfin2, self.custom_params)

Here is the custom_class code:

class CustomWork(object):

    def df2in(self, df1, df2, custom_params):
        dfchanged = pd.concat([df1, df2], sort=True)

        return dfchanged

I get this error:

File "/home/david/git/testapp/app/etl/customclass.py", line 54, in executedf2in
dfresult = custom_class.df2in(df1, df2, self.custom_params)
AttributeError: 'module' object has no attribute 'df2in'

When I inspect the CustomWork instance created it shows under Special Variables in the inspect window, it shows no functions under the CustomWork class

<module 'app.test.custom_work_test' from '/home/david/git/testapp/app/test/custom_work_test.py'>
    <class 'app.test.custom_work_test.CustomWork'>

How do I get it to load the class dynamically with the functions defined therein?