I was suggesting that there were two points that the error could have been "trapped", on entering the ZFW figures into the Laptop and on entering the V speeds into the FMC.
Which is why our performance program has been modified to ask for confirmation of any entered TOW below 300t for the A340-600 and both pilots have to do their calculations independently. Then we compare our figures and enter them into the FMS. Only way to prevent these things from happening.
Cheers,
DL