Cannot Logout of SAML identity provider

I have set up my Auth0 to support SAML2.0 for SSO
Now I want to implement the single log out on my application. I use the following code

            clientID: clientID,
            returnTo: 'Login URL',
            federated: true

this code run ok and redirected me to the login. But when I access the application which use SAML still not logged out.

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