ValueError: not enough values to unpack (expected 4, got 2) for GradCAM++

[r0cketr1kky]

Model: Alexnet
Dataset: CIFAR-10

The code works well with layer_name='features' but I get this error when I change it to layer_name='classifier'

Code:

# GRADCAM++ 
image_path = 'xyz'
image = load_image(image_path)
norm_image = apply_transforms(image, size=32)

model_dict = dict(arch=model, layer_name='classifier_0', input_size=(32, 32))
  
gradcampp = GradCAMpp(model_dict)
output = gradcampp(norm_image)
visualize(norm_image, output)

Error:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-63-fed255ab9edc> in <module>()
      7 
      8 gradcampp = GradCAMpp(model_dict)
----> 9 output = gradcampp(norm_image)
     10 visualize(norm_image, output)

1 frames
<ipython-input-46-e7d860e12ca6> in __call__(self, input_, class_idx, retain_graph)
     70 
     71     def __call__(self, input_, class_idx=None, retain_graph=False):
---> 72         return self.forward(input_, class_idx, retain_graph)

<ipython-input-49-d221b5d1444c> in forward(self, input_image, class_idx, retain_graph)
     32         gradients = self.gradients['value']
     33         activations = self.activations['value']
---> 34         b, k, u, v = gradients.size()
     35 
     36         alpha_num = gradients.pow(2)

ValueError: not enough values to unpack (expected 4, got 2)