something strange...I delete the "reshape"

[Bonsen]

If I run the code directly, everything is right.

one day, I delete these:
#conv10 = Conv2D(2, (1, 1), activation='relu', padding='same')(conv9)
#conv10 = core.Reshape((2,patch_height*patch_width))(conv10)
#conv10 = core.Permute((2,1))(conv10)
....
....
#patches_masks_train = masks_Unet(patches_masks_train) #reduce memory consumption

And when I train the model, I find:
1265s - loss: 14.6464 - acc: 0.2041 - val_loss: 14.2844 - val_acc: 0.2732
Epoch 2/150
Epoch 00001: val_acc did not improve
1425s - loss: 14.1214 - acc: 0.2283 - val_loss: 14.2647 - val_acc: 0.2608
...

Why I must reshape the mask????

[Bonsen]

I find the "categorical_crossentropy" needs (nb_samples, nb_classes)