If you are trying to delete a security group that is assigned to an instance that is running, the security group cannot be deleted. The Dashboard only gives a generic message that the group cannot be deleted without mentioning why.
Instead of letting the user search for the reason, a specific message would be much better:
"Security Group <xyz> is still assigned to instances <abc>. You need to do <cde> before you can delete the group."
If you are trying to delete a security group that is assigned to an instance that is running, the security group cannot be deleted. The Dashboard only gives a generic message that the group cannot be deleted without mentioning why.
Instead of letting the user search for the reason, a specific message would be much better:
"Security Group <xyz> is still assigned to instances <abc>. You need to do <cde> before you can delete the group."