ValueError: Shapes (None, None) and (None, 8, 2, 19) are incompatible

Question

I have changed input size many times but i cant find the issue in my mobilenet v1 224.

# MobileNet block
def mobilnet_block (x, filters, strides):
    
    x = DepthwiseConv2D(kernel_size = 3, strides = strides, padding = 'same')(x)
    x = BatchNormalization()(x)
    x = ReLU()(x)
    
    x = Conv2D(filters = filters, kernel_size = 1, strides = 1)(x)
    x = BatchNormalization()(x)
    x = ReLU()(x)
    
    return x
#stem of the model
input = Input(shape = (256,256,3))
x = Conv2D(filters = 32, kernel_size = 3, strides = 2, padding = 'same')(input)
x = BatchNormalization()(x)
x = ReLU()(x)
# main part of the model
x = mobilnet_block(x, filters = 64, strides = 1)
x = mobilnet_block(x, filters = 128, strides = 2)
x = mobilnet_block(x, filters = 128, strides = 1)
x = mobilnet_block(x, filters = 256, strides = 2)
x = mobilnet_block(x, filters = 256, strides = 1)
x = mobilnet_block(x, filters = 512, strides = 2)
for _ in range (5):
     x = mobilnet_block(x, filters = 512, strides = 1)
x = mobilnet_block(x, filters = 1024, strides = 2)
x = mobilnet_block(x, filters = 1024, strides = 1)
x = AvgPool2D (pool_size = 7, strides = 1, data_format='channels_first')(x)
output = Dense (units = 19, activation = 'softmax')(x)
model = Model(inputs=input, outputs=output)
model.summary()

i tried to change my input size many times but still cant find the compatibility.