Grafana No Data Points

Hello folks,
I have a problem with grafana.
I follow up the influxdb + grafana tutorial but when I try to display a graph, grafana say “No Data Points”…

When I create the data source in Grafana seems oll ok “Data source is working” appear in green but seems database is not populated…

There it is my influxdb.persist

Strategies {
    everyMinute : "0 * * * * ?"
    everyHour   : "0 0 * * * ?"
    everyDay    : "0 0 0 * * ?"
}

Items {
	Est_Temperatura : strategy = everyChange, restoreOnStartup
    Est_Umidita : strategy = everyChange, restoreOnStartup
    Est_Pressione : strategy = everyChange, restoreOnStartup
   Temperatura_Int_Soggiorno : strategy = everyChange, restoreOnStartup
    Umidita_Int_Soggiorno : strategy = everyChange, restoreOnStartup
    Luminosita_Int_Soggiorno : strategy = everyChange, restoreOnStartup
}

and here it is my influxdb.cfg

# The database URL, e.g. http://127.0.0.1:8086 or https://127.0.0.1:8084 .
# Defaults to: http://127.0.0.1:8086
 url=http://192.168.178.175:8086

# The name of the database user, e.g. openhab.
# Defaults to: openhab
 user=openhab

# The password of the database user.
 password=goodpassword

# The name of the database, e.g. openhab.
# Defaults to: openhab
 db=openhab_db

# The retention policy to be used, needs to configured in InfluxDB
# Till v0.13: 'default', since v1.0: 'autogen'
retentionPolicy=autogen

I have rrd4j persist installed and working…is it a problem for influxdb or grafana???

Is there some test to perform to better understand the problem?

Thanks in advance

I have some news:

I’m able to make it work the external meteo data, taken from meteo binding associated server

Est_Temperatura : strategy = everyChange, restoreOnStartup
    Est_Umidita : strategy = everyChange, restoreOnStartup
    Est_Pressione : strategy = everyChange, restoreOnStartup

but i’m not able to persist the date coming from an DHT22 connected to an arduino+esp8266 via MQTT…

In the ZedHome.items file all are Numbers
I don’t understand why influxdb do not persist mqtt data but with other kind of numbers there is no problem …?
any suggesstion?