GroveWeatherPi first time setup

Hello,



I m trying to put together my first RaspPi project with some kids, ( Wind van and rain bucket, GroveWeatherPi connecting all to a Grove connector and raspPi ) 
I got a this error when try to test my project and seems like the light is not ON on GWP !!


Traceback (most recent call last): 
File "GroveWeatherPi.py", line 56, in <module> 
import doAllGraphs 
File "/home/pi/SDL_Pi_GroveWeatherPi/doAllGraphs.py", line 16, in <module> 
import TemperatureHumidityGraph 
File "./graphs/TemperatureHumidityGraph.py", line 16, in <module>
import matplotlib 
ImportError: No module named matplotlib





I have Python 2.7.16 version installed


thanks