This post contains steps to help debug problems with using the "SWD over Link2" and "SWD over LPC11U35" interfaces.
1. I don't have entries in the Interfaces list
For LPCxpresso boards make sure to install the DFU Link jumper and for LPC-Link2 boards make sure to remove jumper JP1. Connect the boards to your PC and make sure they are recognized by Windows in the Device Manager as "LPC device". Then start Flash Magic. At this point an LED on the boards should start flashing.
2. The LED doesn't start flashing
Check the board has been recognized by the PC. In Device Manager look for "HID-compliant vendor-defined device". Right-click and choose properties. Then click on the Events tab and scroll down in the information box. You should see something like "Parent Device: USB\VID_1FC9&PID_F059\xxxxxxxxxx" where xxxxxxxx is the interface serial number.
(http://forum.flashmagictool.com/index.php?action=dlattach;topic=4525.0;attach=944)