MJ,
After Credit release, In sales Order that quantity has been confirmed for new Order.
In CO09 now quantity is reduced.
In the Availability check configuration, One time delivery has been selected.
That means if the entire sales order, line item qty is not available, for the delivery date given in the sales order; then zero qty is confirmed by the system.
If the ATP qty = 9402 and sales order has qty = 9405; then the system confirms zero qty. In the case of one time delivery. That is exactly what is happening in your case.
There are other options e.g. Complete delivery, Delivery proposal. Read about these.
Now there are two parts / process steps happening -
1. Before the credit check - Some qty is being reserved. You / user is going in to the popup Availability check and selecting the qty = 9402.
2. After the credit check - System is blocking the sales order due to the credit check. After releasing the sales order, the system does an availability check again.
Here the system goes for One time check and finds that 9405 qty is not available. Therefore confirming zero qty.
If you change the One time delivery to Delivery proposal, then system shall give you multiple schedule lines.
Also field "Check without RLT" has to be deactivated.
Side comment - Look at vemuri santosh's post (in this thread)