first check your devise manager for your usb to serial port.
if it is in the list it is fine
or else update your drivers
if it is displaying the port as COM3 ..COM5…etc
select the perticular COM port in the flash magic window
at first i got the same problem but fially i found a solution
recently i found a USB to UART (TTL) converter from silicon chip it comes with a driverif you
use it you dont need a MAX232 IC you can directly connect the RX and TX