could it be the software its self because I bought it from here http://www.cash-register.info/acatalog/ ... ogram.html as I did not have the origional cd from sharp

It could be the software. Vista isn't listed as being compatible, but have you tried running the software as an administrator? Right click on the software icon, then choose 'Run As Administrator'. However we still don't know if the serial to usb is working properly. Do you have anything else that needs a serial port to connect to a pc?

unfortunatly not. I have set up the software to run in compatibility mode as an admin, the driver does install when I connect the usb to serial cable to my computer

Just a thought. Does the company you bought not support the software?
I normally gave the software free when people bought the till but did say about the possible Vista compatibility issue on pc's without serial ports. I'll need to have a close look at the program structure to see what the problem is, assuming everything else is ok.

While I'm looking at this, can you tell me if you have Vista service pack 2 installed?

yes I do

It looks like there isn't a way to make the easy programming tool work with Vista or higher. My copy running on Windows 7 32 Bit stopped working.
Sharp don't support it because it's free.
One thing I haven't tried it on is Windows 7 Pro running XP as a virtual machine, however I think that's a bit too much to do for such a small program.

If you have a Windows XP disk, it is possible to install XP to run as a virtual machine on Vista. If you feel confident enough I can tell you how to do it.