Winup26 via USB to serial adaptor?

Hello,

I suppose I might as well ask this here, just in case anybody wanders along who can advise me. I've seen a couple of other posts on related issues, but none as yet have helped me.

I am trying my Vantage X221TS CI receiver which I haven't used for a while, and I am wanting to load different firmware releases and also softcams.
My Windows Vista pc doesn't have a serial/RS232 port, so I have a Prolific USB to serial adaptor, to connect to the Vantage via a null modem cable.

I am having great trouble when using Winup26, in that data transfers usually appear to start then fail. Once or twice they have succeeded, but I have no idea which factors are affecting it.

It seems however, that I can load either .dlp or .hdp firmwares using the Vantage Channel Editor/ Loader version 2.3, but softcam uploads fail with a 'communication timeout'.

So, is there a method or tool I am missing here?

Many thanks,
Lee
UK