It's possible that you have a remarketing campaign and Opteo can't detect it.
Opteo checks for display campaigns with audiences associated to them. If it can't find any, it will flag up a task explaining how to create a remarketing campaign.
We also won't be able to detect your remarketing campaigns until they have accumulated a few impressions. If you've set up a remarketing campaign and Opteo is still pestering you about it, just dismiss the task for a week, and if everything has been set up right, that improvement task won't come back :)