I am trying to use grafana along with zabbix to find network saturation points and bottlenecks.

As part of that I was building a panel to show bits_sent + bits_rec / port_speed stats from Zabbix using the plugin, however when using an expression on the variables in the panel I see the “No Data” message.

Why would metrics that are clearly being collected individually not function when expressions are run against them?

I have tried looking at the grafana logs and they really aren’t the most helpful in figuring out why this is happening. Someone else has to have run into this issue?