How long has the retargeting pixel been installed in your store? In order for you to have a bigger reach you need a lot of people to visit the page where you have the Facebook pixel installed.
Then the same people need to log in to Facebook for them to get targeted by it. It may be that you haven't accumulated too many people who have visited your store yet. if you don't have a lot of traffic, that may take some time.
Content Marketing & Growth at Compass.co
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