Different available packages in TensorFlow virtualenv?
I can't offer any suggestions as to why your virtual environment can't find the packages (I'm not familiar with anaconda). The only thing that comes to mind is a PATH problem.

Perhaps try installing the package with the following command:

conda install -n yourenvname [package]


or, in your case:

conda install -n tensorflow h5py



  To install additional packages only to your virtual environment, enter
  the following command where yourenvname is the name of your
  environemnt, and [package] is the name of the package you wish to
  install. Failure to specify “-n yourenvname” will install the package
  to the root Python installation.


source: https://uoa-eresearch.github.io/eresearch-cookbook/recipe/2014/11/20/conda/