Indeed the error was:
Est_T_Max : strategy = everyMinute, restoreOnStartup
instead of
Est_Temperatura : strategy = everyMinute, restoreOnStartup
For sure my error (sorry about stupid error 
)
BUT i have another question, because in my opinion make chart it is a little triky and hostile for noobs like me.
Now , due to your help, I’m able to display Temperature chart correctly (see photo)
Where I have to modify the code to display also Tmax and Tmin in the same Chart???
I Know guy it is easy and maybe i can manage by myself, but I hope these question can help also further people with the same problems and If i understand well the various arguments maybe I can help someone other in the forum.
my actual files are that:
rrd4j.persist
Strategies {
everyMinute:"0 * * * * ?"
everyHour : "0 0 * * * ?"
everyDay : "0 0 0 * * ?"
default = everyChange
}
Items {
Est_Temperatura : strategy = everyMinute, restoreOnStartup
Est_T_Min : strategy = everyMinute, restoreOnStartup
Est_T_Max : strategy = everyMinute, restoreOnStartup
Est_Umidita : strategy = everyMinute, restoreOnStartup
Est_Pressione : strategy = everyMinute, restoreOnStartup
}
items file
Group Meteo
Number Est_Temperatura "Temperatura [%.1f °C]" <temperature> (Meteo) {weather="locationId=myhome, type=temperature, property=current"}
Number Est_T_Min "T Min [%.1f °C]" <temperature> (Meteo) {weather="locationId=myhome, type=temperature, property=min"}
Number Est_T_Max "T Max [%.1f °C]" <temperature> (Meteo) {weather="locationId=myhome, type=temperature, property=max"}
And the sitemap
Frame {
Switch item=Meteo_Grafico_Temperatura label="Grafico Temperatura" mappings=[0="Hour", 1="Day", 2="Week"]
Chart item=Est_Temperatura period=h refresh=6000 visibility=[Meteo_Grafico_Temperatura==0, Meteo_Grafico_Temperatura=="Uninitialized"]
Chart item=Est_Temperatura period=D refresh=30000 visibility=[Meteo_Grafico_Temperatura==1]
Chart item=Est_Temperatura period=W refresh=30000 visibility=[Meteo_Grafico_Temperatura==2]
}
I try by myself to make a very fast test but it doesn’t work
I try to display the whole group
Frame {
Switch item=Meteo_Grafico_Temperatura label="Grafico Temperatura" mappings=[0="Hour", 1="Day", 2="Week"]
Chart item=Meteo period=h refresh=6000 visibility=[Meteo_Grafico_Temperatura==0, Meteo_Grafico_Temperatura=="Uninitialized"]
Chart item=Meteo period=D refresh=30000 visibility=[Meteo_Grafico_Temperatura==1]
Chart item=Meteo period=W refresh=30000 visibility=[Meteo_Grafico_Temperatura==2]
}
But some other needed =)
Thank you at all the replayers !!! OpenHAB is YOU guys!!!
thanks for asking 
