> ## Documentation Index > Fetch the complete documentation index at: https://docs.abtestly.com/llms.txt > Use this file to discover all available pages before exploring further. # Snippet is on the page but nothing happens > A diagnostic ladder for the most common install issue: the tag is in the HTML but no variants apply and no beacons fire. You dropped the snippet in ``. You verified it is there in view source. You opened your test page in a fresh tab. Nothing happens. Nine times out of ten it is one of the five things below. ## 1. `window.__ABTESTLY_CONFIG__` is undefined The snippet did not load. Not "did not run", did not even load. ```js theme={null} window.__ABTESTLY_CONFIG__ // undefined ``` Check, in order: * **Is the snippet actually in ``?** Right-click the page → View source. Search for `abtestly`. It has to be a `