Root error at rooting

[gerwinvis]

When i try to root my xperia-z i have to flash a older firmware (with flashtool)... when it is in flash mode it gives the next error:
"Error flashing. Aborted
Drivers need to be installed for connected device.
You can find them in the drivers folder of Flashtool."

I have installed the "xperia z driver" and the "Flashmode driver" but it does not work...

I can't find the same problem on google...

 

[Slug]

Try rebooting the system and connecting the handset to a different USB port; that can sometimes resolve this sort of error. If not, reinstall the drivers.