Mayavi does not recongise installed Traits.

I tried to install Mayavi into my anaconda environment (python 3.5):

conda install -c menpo mayavi=4.5.0
conda install -c anaconda wxpython=3.0.0.0
conda install pyqt
conda install qt

But when I try to run the example from http://docs.enthought.com/mayavi/mayavi/auto/example_surface_from_irregular_data.html I get the error message

ImportError: Could not import backend for traits

with the explanation:

> Make sure that you have either the TraitsBackendWx or the
> TraitsBackendQt projects installed. If you installed Mayavi with
> easy_install, try easy_install . easy_install Mayavi[app]
> will also work.
>
> If you performed a source checkout, be sure to run 'python setup.py
> install' in Traits, TraitsGUI, and the Traits backend of your choice.
>
> Also make sure that either wxPython or PyQT is installed. wxPython:
> http://www.wxpython.org/ PyQT:
> http://www.riverbankcomputing.co.uk/software/pyqt/intro

I get the same error message if I just try to run `mayavi2` from the console.

From http://docs.enthought.com/mayavi/mayavi/installation.html?highlight=installation I got that I could install it via pip with `pip install mayavi`, but that resulted only in the messages that "Requirement already satisfied", among which is

> Requirement already satisfied: traits in /anaconda2/envs/myenv/lib/python3.5/site-packages (from mayavi)

I searched the web and tried to find anything to setup, but couldn't find anything. What to do?