Addtion of two mean values does not work

Hi,
i have this query:

SELECT
mean(“smartmeter_v”) AS “Smartmeter”,
mean(“solarlog_v”) * -1 AS “Solarlog”,
mean(“solaredge_v”) * -1 AS “Solaredge”,
mean(“solarlog_v”) + mean(“solaredge_v”) AS “Verbrauch”
FROM
( SELECT value as “solarlog_v” FROM “solarlog_akt_leistung” WHERE $timeFilter ),
( SELECT value as “solaredge_v” FROM “solaredge_akt_leistung” WHERE $timeFilter ),
( SELECT value as “smartmeter_v” FROM “smartmeter_akt_leistung” WHERE $timeFilter )
WHERE timeFilter GROUP BY time(__interval) fill(null)

The Line

mean(“solarlog_v”) + mean(“solaredge_v”) AS “Verbrauch”

is not working as expected. There is no value returned. What i have to do to get the sum of solarlog_v and solaredge_v?
A new Value for solarlog_akt_leistung is written every 15s
A new Value for solaredge_akt_leistung is written every 5s

BR

mode

Build the seperate query for each value, then try to utilize Transform - Add Field from Calculation

Thanks, after upgrading grafana i found the transform tab. Now it works as it should!