Hi,
It looks like that the password you gave is not the right one for the "production" mode.
The data is encrypted and if the password is not good, SagePay can't decrypt and extract the parameters.
Are you sure that you're using an account in production and not a sandbox one ?
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.