Registration form is not sending password mail to new user

My problem is whenever new user try to register on my site http://desertareafsbo.com/
They got successfully register but they don’t get the mail for their password, Being admin when i check my admin i can see new user successfuly register and as admin i also got email that someone has register on my website.

Although new user does not have their password, if they try to login , there is a link “lost password” if they click on lost password and provide their registered email adddress they got a link via mail for changing the password.

I don’t know when they are getting link for changing password then why are they not getting the password when they register first time.

And one more thing contact form is working fine then why not registeration form…..if some one use contact form to send me message i being admin receive the email.