Does your system register anything being connected to the usb at all? Are you connecting it to a powered usb port? (though most sata to usb converters actually have two usb ends, one for power, one for data...so power shouldn't be an issue. ...unless you haven't connected any power...) What kind of drive do you have? What converter are you using?
Cables could be useless, the HD could be dead, so many things to test.
Can you attach the HD? directly to a motherboard controller port? Do the cables work with another HDD? Can you attach any other USB device, like a thumb drive? Trying to figure out where the problem is.