Thanks for the image.
Misidentification of this stamp (Scott 579) is common. With any less common stamps it is important to verify the correct identification and this often requires a good understanding of details. Approach with an open mind and start by learning as much as you can.
This particular stamp was issued over the span of many years, a 'workhorse' for the postage using public. Over the long production span, several varieties were released, some common and some not common. You might start on this webpagehttp://www.stampsmarter.com/1847usa...ntifier.html
as an overview of the different types. The site has much more info if you poke around on it.
Do you have a perforation gauge and do you know how to determine the perforations on a stamp?