What version of vBShout do you have installed? I think you're the first person to experience (or at least report) this problem.
At any rate, it can be fixed manually by doing this:
Go to
DBTech - vBShout -> Instance Management -> Add New Instance.
Set the options as per this screenshot:
Attachment 123420
Then once you've saved, hover over the "Edit" link for this newly created instance and note down the Instance ID. So if the link is [yoursite]/admincp/vbshout.php?do=modifyinstance&instanceid=26 the instance id is
26.
Go to vBulletin Options -> DragonByte Tech: Forumon - [DBTech] vBShout Integration Settings and set the Instance ID setting to the number you found in the previous step, then click Save.
It will then be safe to re-enable the Integration.
Hope that helps
Fillip