HTTPS Site (NTLM) keeps prompting for login

Hi,

I have a web application on http where authentication method is set to NTLM. When users access this web application,

they are not asked to enter their credentials.

Now I've created another web application, but on HTTPS protocol (enabling SSL) and keeping Integrated Windows Authentication,

NTLM, as authentication method. Every time when users try to access this site, they are asked for password.

What do I need to do so that users don’t have to enter their credentials every time?

Thanks,