Hey realtek,
Bare this in mind when you code:
mail(string recipient, string subject, string body, string additional_headers)
Keep in mind that each extra header must be separated by a single newline character.
Im not sure what you are trying to achieve with your code below, but try the above structure out making sure that you separate each parameter with a " , " and each variable should be enclosed within the " " parenthesis.
Hope that works.