Ensuring Emails go to "Primary" tab
Option 1: Drag the email from promotions and drop it directly on the "Primary" tab. In the yellow pop-up box that will appear at the top of the page, select yes, to continue to receive all emails from that person into your primary inbox.
Option 2: Or you could go to Settings > Inbox and deselect Promotions as one of the categories you're using. If you do that, all of the emails you receive which would have gone to Promotions will now go to Primary. That may not be ideal though if you do still want Gmail to recognize and categorize other emails as Promotions. However, you could create your own tab categories and designate certain senders as belonging to those categories.