Look at your browser’s network tab in the developer tools to verify that a request was issued.
Look for the HTTP request in your server’s console to see if the request was made, and received a 200 and not a 404.
Use your browser’s developer tools console to see if the name for that function was defined.
Note that your attempt to put a reference to the function inside that script tag is usually not going to work, because that will frequently be executed before the http request for the JavaScript file is executed and almost certainly before the response to that request is received and processed. You would need to write a script that can wait until all assets are loaded before running.