Cannot connect to PC

Hi folks,
I'm new here but I have a number of Yaesu transceivers so I'm used to their intricacies! 

I can't seem to get the radio to talk to my PC and vise versa.
I purchased the FBTVR5K software and the correct USB RS232 cable from Steve at www.ewwa.net/shop

I've installed the CP210x_VCP_Windows drivers and set the correct com port (in this case Comm 8) and adjusted the baud rate to 9600 (I've also tried 4800 and I'm aware that 57600 doesn't work)for the software.

I've also tried setting the Com port on the computer to 7 and 6 (as well as adjusting the software) but to no avail.

I've even tried all this on a different PC but I still can get it to work.

I've double checked and I definitely have the correct cable.

I'm beginning to wonder if I have the correct drivers?
The ones I've used are here: 
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx

If anyone has any suggestions I'd greatly appreciate them.

Cheers,

Aubrey