DPU-PYNQ on Ultra96v2 does not work well

Hi,

I followed DPU-PYNQ quick-start on the link below.

Then, I tried dpu_mnist_classifier.ipynb and it worked well.
But dpu_mnist_classifier.ipynb with keras.datasets.mnist ( original ipynb used mnist ) had poor accuracy. All prediction results were ‘1’.

Does anyone have any idea?