Hello, I have openhab 3.1 on an ubuntu server.
I use some Xiaomi temperature and humidity sensors (LYWSD03MMC). After a lot search, I can get the temperature and the humidity from this sensor in openhab. But I have only access of the last value, when I open the analyse view, I have nothing. Maybe I have to active something, but I don’t know what.
Sorry for my poor english, and thanks for your answer. 
How long have you waited before trying to view the graph? I think I read somewhere that it can take some time before the openHAB graph populates, irrespective of how many times your device actually sends out messages.
The sensors work since two week ago, and a new temperature value arrrived every 10 minutes.
Persistence is configured to collect the values over time ?
How you configure that?
OK, I think this is the problem, nothing is configured. So I will do that, and I come back to say if it works after. 
What type of Item are you using? The built-in charting and default persistence works with numbers.
Problem fixed. After the persistence service installation, graphics begin to de draw.
I use the generic MQTT things.