short sale involving a second mortgage?

hi, i am a first time user. we sold our house in california as a short sale in dec 2008. both loans showed up on our credit report a year ago, one as settled the second as charged off. we are now trying to buy a house and a debt collector is contacting us for payment on the second mortgage. we have been told that the debt was sold to this new company. now two years after the short sale on the house we are being told we must repay this debt. both loans were originally held by the same company, national city. this is now showing up on our credit report as being owed instead of the charge off it has been for more then a year. i thought in california if you secured a loan against property then all debts must be settled prior to the transfer of the deed, which did happen. any advise on how to settle this nightmare would be appreciated.