RuntimeError: Failed to connect RL API

[o00000o]

I follow the steps in https://github.com/deepmind/lab/blob/master/docs/users/build.md
This command runs without problem bazel run :python_random_agent --define graphics=sdl --
--length=10000 --width=640 --height=480
bazel build -c opt //:deepmind_lab.so and bazel test -c opt //python/tests:python_module_test No problem
But RuntimeError: Failed to connect RL API appears when I run bazel run -c opt //:python_random_agent