Could not find variable posterior_bias_loc_1

Keras
,
#1

I am working on modification on VAE to make it Bayesian VAE. To do so, I follow the structure on tfp.experimental.nn.ConvolutionTransposeVariationalReparameterization  |  TensorFlow Probability
I have the following code that is part of VAE model:

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That is work very well. However, Once I tried to modify it like the following.

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I got the following error for the last line. Is there anybody that can help me resolve it:
tensorflow.python.framework.errors_impl.FailedPreconditionError: Could not find variable posterior_bias_loc_1. This could mean that the variable has been deleted. In TF1, it can also mean the variable is uninitialized. Debug info: container=localhost, status error message=Resource localhost/posterior_bias_loc_1/class tensorflow::Var does not exist.
[[{{node JointDistributionSequential_2/sample/posterior_bias_1/sample/Normal_4/sample/ReadVariableOp}}]]