How to share cookies between domain and subdomain with nookies?

I'm using nookies and I'm having a hard time sharing cookies between my app and website.

This is the code I use on my app.mydomain.com file:

       //setCookies to main domain
        setCookie(null, 'jwt', loginResponse.jwt, {
          maxAge: 30 * 24 * 60 * 60,
          path: '/',
          domain: 'mydomain.com'
        });

I guess I'm doing something wrong since it's not working.