New Users Email

I have new users that create accounts on my website. When they create a new account using the link posted in the header, I am sent an email alerting me that I have a new user. Yet, when a new user creates an account using the login button, and then clicking create a new account… I am not sent an email alerting me to the fact that I have a new user. How do I fix this glitch or what is causing this glitch.