Does the DVD writer have an external power adapter ?
If you try to power the USB DVD writer from an USB port, it may try to draw too much power, exceeding the 500 mA rating an USB 2.0 port can handle. Plus, if you populate the USB 2.0 ports with many power-hungry devices, they may not be able to even handle 500 mA. ( USB 3.0 port, 900 mA )
In such cases, you can buy a powered USB hub and connect your DVD writer to it, rescuing your DVD writer from becoming paperweight.