It is fairly common that order is placed on your website but you did not receive any payment. This happens for several reasons namely:

1. the customer changes his/her mind;

2. the customer faces problem when making payment (you can do a test order to check whether your payment gateway is working properly);

3. the customer needs a discount before making payment;

4. the customer needs someone to call him/her back to address his/her questions;

5. the customer places order just to check the shipping fee.

6. the customer is waiting for his/her customer to pay before making payment to you.

7. The customer place the order and make payment later.

8. Other reasons

In order to find out the real reason why the customer does not pay, it is advisable to contact the customer personally.