Set the Login with Redirect for SSO to Sign-up by screen_hint

I’m using the Auth0 Single Page App SDK for Angular.js (auth0-spa-js: 1.12.0). The following code ( New ULP is used) unfortunately does not navigate to the sign-up page instead of the login page.

return auth0.loginWithRedirect({
redirect_uri: window.location.origin,
screen_hint: ‘signup’,
}).then(function () { …

Can you please help me with this problem?