Fail to load densebox

My environment:
Board: ZCU104
Image: pynq 2.6
vitis-ai: docker 1.2.82
pynq-dpu 1.2

I can compile cf_densebox_wider_320_320_0.49G_1.2 successfully, and get the information as shown below.

When I load the model from the previous step and feed into dnndk by

from dnndk import n2cube
overlay = DpuOverlay("dpu.bit")
kernel = n2cube.dpuLoadKernel("densebox")

When I run it through jupyter notebook, I meet the problem like this.

BTW, I can run the dpu_yolo_v3 example in pynq-dpu normally.

Supplementary description:
My problem is that I set up the environment according to official documents, and also compile the model successfully. Is there anything I need to modify to load the model through dnndk?

Since I can load and infer the same model through VART, the model should be fine.