Here are a few things to check:
1) Make sure credit card processing is set up in SuccessWare by choosing File > Security from the menubar and clicking the Credit Cards tab in the window that appears. You must have an active merchant account. Internet-based credit card payment processing is provided by PayJunction. They have great rates for SuccessWare customers and provide client credit card information storage on their secure servers, which is an essential part of SuccessWare's payment plan capabilities. For rates, answers to all of your questions, and to apply for a merchant account, fill out this form.
2) If you are running Mac OS X, a window may appear the first time you plug in the reader stating that you cannot use the new "keyboard" until it is identified. Simply press any key on your regular keyboard, and then close the window and the reader will work fine.
3) Make sure the light on the reader is lit. If it isn't, the reader is defective, it isn't plugged in properly to a functioning USB port, or the system is not recognizing the device. Contact POSWorld for support at http://www.posworld.com/supporthelp.html.
4) Try opening a text editor application such as NotePad on Windows or TextEdit on Macintosh and swiping a card. The card's track information should appear within the open window in the editor just as if you typed it on your keyboard. If it doesn't, there is probably something wrong with your reader. Contact POSWorld for support at http://www.posworld.com/supporthelp.html.