Upgrading Receiver trough 25 pin serial

[proantibiotic]

Hello,


My Receiver is Opticum / Orton 4100c

I'm trying to upgrade my receiver firmware.

The receiver has rs232 9 pin male connection.
My desktop computer has 25 pin serial female connection.
So I bought null modem rs232 cable one end female 9pin, the other 25 pin male.
But as hard as I try to follow instructions. It just doesn't connect. I use attached software and I use windows vista.
When I select firmware and press next, it says "wait for serial connection" and then nothing happens. I tried to connect and disconnect the receiver, on, standby, off modes. but had no luck.

So my question is what is wrong with my setup?

1. OS?
2. Cable?
3. Connectors?
4 Software?

Any help would be appreciated! :)