can't detect bluepy.btle when executing findMambo.py

Hi, i get this error:
```
Traceback (most recent call last):
  File "findMambo.py", line 1, in <module>
    from bluepy.btle import Scanner, DefaultDelegate
ImportError: No module named btle
```
when I execute the findMambo.py. I installed all the packages that have to be installed but still having this error. Can some one help me.
I'm developping on ubuntu.