Hello,
Please check the below relevant settings.
Check in OIM9 for your notification type whether there exist a check on "AutoContractDet".
This setting will automatically determine your contract on the notification where you linked the equipment.
Check in OIAL(Screen parameters) whether sales order and sales document item are grayed out for change for your notification type.This will allow not to change the sales document.
Also, check whether notification type is assigned to your relevant service order type in the configuration"Define Notification and Order Integration". This setting allows to create notification automatically from the service order.
Regards
Srikanth