If you directly import your Unity environment without building it in the editor, you might need to give it additionnal permissions to execute it.
`chmod -R 755 *.x86_64`
On Windows, you can find instructions [here](https://technet.microsoft.com/en-us/library/cc754344(v=ws.11).aspx).
### Environment Connection Timeout
If you are able to launch the environment from `UnityEnvironment` but then recieve a timeout error, there may be a number of possible causes.
* _Cause_: There may be no Brains in your environment which are set to `External`. In this case, the environment will not attempt to communicate with python. _Solution_: Set the train you wish to externally control through the Python API to `External` from the Unity Editor, and rebuild the environment.
* _Cause_: On OSX, the firewall may be preventing communication with the environment. _Solution_: Add the built environment binary to the list of exceptions on the firewall by following instructions [here](https://support.apple.com/en-us/HT201642).
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