How to transfrom the mymodel ssd_300_vgg.pb to IR and use your code to detect

[chirs123456]

LaptopPc+ x86_64+ Ubuntu1604 ssd_300_vgg
use the program from https://github.com/pierluigiferrari/ssd_keras

how to convert the .pb model to IR?
l use
python3 mo_tf.py --data_type FP16 --input_shape [1,300,300,3] --input_model /path/to/my/pbmodel
it's wrong.
[ ERROR ] Shape [ 1 3 -1 256] is not fully defined for output 0 of "conv8_2/convolution". Use --input_shape with positive integers to override model input shapes. [ ERROR ] Cannot infer shapes or values for node "conv8_2/convolution". [ ERROR ] Not all output shapes were inferred or fully defined for node "conv8_2/convolution". For more information please refer to Model Optimizer FAQ (<INSTALL_DIR>/deployment_tools/documentation/docs/MO_FAQ.html), question #40. [ ERROR ] [ ERROR ] It can happen due to bug in custom shape infer function <function Convolution.infer at 0x7fe94897d378>. [ ERROR ] Or because the node inputs have incorrect values/shapes. [ ERROR ] Or because input shapes are incorrect (embedded to the model or passed via --input_shape). [ ERROR ] Run Model Optimizer with --log_level=DEBUG for more information. [ ERROR ] Stopped shape/value propagation at "conv8_2/convolution" node. For more information please refer to Model Optimizer FAQ (<INSTALL_DIR>/deployment_tools/documentation/docs/MO_FAQ.html), question #38.
how to correct convert? need other parameter? and parameter's content?

And what should l change the code if l use your code to detect.