Payment gateway not coming up

[Gunther77]

When a customer selects to purchase hosting from me and then completes the order process.
The customer fills all their details and then selects complete order.
No Payment option comes up.
The system then takes them into their client area, one can see the invoice.
Why is the customer not asked to pay before the process is completed?
I would expect a paypal window to open so that the customer can make a payment.

regards
Gunther Wallendorf