Stephen

Sorry, i don't understand. The pin 9 of DB9 is RI (Ring Indicator) , please do not connect it at all (it in an output for DCE(modem)  and an input for DTE (PC)

use only  Pin 2 3 and 5 (0Volts)

and if you want, make a bridge between RTS and CTS (Pin 7 and 8)

and if you want make a bridge between DTR and DSR (Pin 4 and 6)

for CD, it is depend of what you expect on the other side

and/or just check the forum about

UART cable pin-out

Could you give us the model of your USR-Serial port cable ... i still be a little surprised

Eric