Cant Pull data from InfluxDB to Grafana

Hi All,
I am trying to implement TIG stack to monitor the system metrices of different system.
As of now I have installed Telegraf in 3 agents and in Centos I have hosted InfluxDB and Grafana.
So in Sys - A - We have Grafana , Influx DB and Telegraf (CENTOS)
Sys- B - We have telegraf agent(UBUNTU)
Sys - C - We have telegraf agent (UBUNTU)
Sys B and Sys C are sending the metrices to the influxdb and I can see the data in the measurements.
Now the problem is while I am connecting the InfluxDB to Grafana from Sys-A, I am only able to visualize the information of System A in which the grafana is hosted.
I have tried to change the host in the query section of grafana , still its not pulling any data.

Please help me regarding it.