Enum of classes with polymorphism

Question

In the following Enum inheritance calling a polymorphic method on the members' value gives an unexpected result.

from enum import Enum

class Activation:
    def activate(self, value):
        print("in activation")
        pass

    def derivative(self, value):
        pass

class Relu(Activation):
    def activate(self, value):
        print('in relu')
        return max(0, value)

    def derivative(self, value):
        return 0 if value<= 0 else 1

class Activations(Activation, Enum):
    RELU = Relu()
    #TANH = Tanh()
    #SIGMOID = Sigmoid()
    #SOFTMAX = Softmax()

activ1 = Relu().activate(11)  # output: in relu
activ2 = Activations.RELU.activate(11)  # output: in activation

activ2 output is 'in activation', while desired output is 'in relu'.