# Diag: metrics explorer empty after install

**Symptom (exact):** agent installed and running, but Metrics Explorer shows no data for the host, not even system metrics.

**Likely causes:** (a) agent not submitting (key/site), (b) querying the wrong thing, (c) clock skew.

**Confirm:**

1. `datadog-agent status`: forwarder accepting payloads? If 403/connection errors, stop here and run the 403 or proxy runbook. This is not a metrics problem.
2. In the app, Infrastructure, Hosts: is the host listed at all? Not listed means nothing is submitted (cause a). Listed but metrics empty is weirder, keep going.
3. Query `system.cpu.user` with no tags and a 1-hour window. System metrics are unconditional: if even these are missing, submission is broken.
4. Check the host clock against NTP. Skew breaks TLS to intake.

**Fix:** fix submission (key/site/proxy), or fix the query (metric name spelling, tag filters, wider window).

**Verify:** `system.cpu.user` graphs within two minutes of the fix. Then check your custom metric. Rule: system metrics first, custom second. If system metrics flow and yours does not, the emitter is the problem, not the agent.