Sage Pay Error : 4001 : The VendorTxCode

Please help,
We are using Sage pay.
We have already used this sage pay account with Virtuemart, so there has already been orders processed through sage pay before we started using Virtuemart.

Sage pay do not allow duplicate TxCodes , how can I amend the TxCode that is sent to Sage pay so I do not get this error?

Regards,
Sean R.

Hi there,
I have managed to fix this error.

I had to go into the database and change the order id in table 'hikashop_order'

I started the value at 10000, so that order ids were not duplicated