My b2evolution Version: Not Entered

Hi Anyone
I have just setup b2evolution ver 1.9.3 on Windows 2000 server. I run Apache server with MySQL and PHP5 using XAMPP tool. I am having problem with email validation whenever a nuew user log in and try to verify thru email. I got this error "Sorry, the email with the link to validate and activate your password could not be sent.
Possible reason: the PHP mail() function may have been disabled on the server."
I have trying to find what's wrong but I am not sure where to look. I have Moodle running on the same server and the email works just fine. Could anyone please HELP. :'(