Aggregating multiple range vectors (avg of avg_over_times(m[d]))

Grafana Prometheus
1

Hello everyone,

I want to calculate the average of multiple avg_over_time range vectors.

avg_over_time(probe_success{job="http",instance="google.com"}[$__interval]) + avg_over_time(probe_success{job="http",instance="youtube.com"}[$__interval]) + avg_over_time(probe_success{job="http",instance="facebook.com"}[$__interval])

But when I only run this query, it already returns No data.
Can you help me with that?

Thanks!