OK Google "does not work - it can be because

Have you activated "OK Google" on your smartphone?

In order to use Google's automatic voice search by voice command on your smartphone, you have to activate it in some cases. That's how it's done:

First, make sure you have the latest version of the Google app installed on your smartphone. The best thing to do is to open the Google app in the Play Store. If necessary, tap "Update". Tip: The latest version is always available from us as an APK download.
Open the Google app and tap the side menu at the top left.
Then go to Settings> Language> OK Google Detection.
Activate the switch next to the menu item "About the Google app" (see screenshot).
If this does not lead to the desired success, also activate the switch next to "On every screen" and follow the instructions to set your voice to Google.

If "OK Google" is already activated and the voice search does not open, this can also have other errors. How to check them quickly, read here:

Clear the cache in the Google app.
If necessary, uninstall and reinstall the Google app. If uninstallation is not possible, remove the app data using the application menu or your app manager.
With some smartphone models it is also possible that the "OK Google" recognition only works in English. To do this, you can switch to English using the language settings of the Google app, but you must then use the entire service in the selected language.
You can also retrain the language model using the "On every screen" setting. In some cases it makes sense to complete the training in English and then switch back to German.
There may also be a defect in your cell phone microphone.
You can also try disabling all accessibility features (such as Dashclock Whatsapp).

You can read about how to create your own voice commands in Google Now on the next page.