Some orders are received in On-Hold Section, that's mean you don't have enough credit in your balance
So the orders will be there till you recharge your account
When an order going to be On-Hold, you will receive an email to notify you about this and also tell you how much time it will be there.
When the On-Hold time expired, the order will be canceled and you need to replace a new order again on your website.
For charge/recharge your account: