I cant find what’s wrong. The code runs throough some iterations but stops with an error at a certain point.

```
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-73-7e580406a9e8> in <module>
6 "stride": 2}
7
----> 8 Z, cache_conv = conv_forward(A_prev, W, b, hparameters)
9 z_mean = np.mean(Z)
10 z_0_2_1 = Z[0, 2, 1]
<ipython-input-72-5ab1f4c28a9c> in conv_forward(A_prev, W, b, hparameters)
103 weights = W[:,:,:,c]
104 biases = b[:,:,:,c]
--> 105 Z[i, h, w, c] = conv_single_step(a_slice_prev,weights,biases)
106
107 # YOUR CODE ENDS HERE
<ipython-input-68-f329765a0740> in conv_single_step(a_slice_prev, W, b)
23 # Z = None
24 # YOUR CODE STARTS HERE
---> 25 s = np.multiply(a_slice_prev,W)
26 Z = np.sum(s)
27 Z = Z + float(b)
ValueError: operands could not be broadcast together with shapes (3,0,4) (3,3,4)
```