Database migration issue for custom plugin - OJS 3.3.0.17

Hi,
I’m creating a plugin that needs a custom table in db. I created migration for it in the same way as for other plugins that come with a fresh installation of OJS. I also added the getInstallMigration function in plugin class. What am I missing? Because migration is never performed during plugin installation. No errors appear either. Other than that plugin is visible after installation and works. My OJS version is 3.3.0.17.

Cheers