Unable to export model

Hi all

i wish to export the pretrained gluoncv model to its json and params but unable to do so. i tried the example in the https://gluon-cv.mxnet.io/build/examples_deployment/export_network.html
which i have no issue. But when i tried:

net = gcv.model_zoo.get_model(‘i3d_resnet50_v1_hmdb51’, pretrained=True)
export_block(’./model’,‘i3d_resnet50_v1_hmdb51’, net)

it doesn’t work and output errors:
ValueError: Children of HybridBlock must also be HybridBlock, but i3d_resnet50_v1_hmdb51 has type <class ‘str’>. If you are using Sequential, please try HybridSequential instead.