RuntimeError: Given groups=1, weight of size [16, 1, 3, 3], expected input[16, 3, 1, 28] to have 1 channels, but got 3 channels instead

Question

I know my images have only 1 channel so the first conv layer is (1,16,3,1) , but I have no idea why I got such an error.

Here is my code (I post only the related part