Problem with DB publishing

On all our content types we have sys_CheckBoxGroup controls, now when I follow Database publishing example from Rhythmyx Implementation Guide and trying to publish to Database I am getting following error:

Serious problem This is a multi valued property

I am assuming that this error has to do something with sys_CheckBoxGroup since this is the only control on the content type with “multiple values”.
Does anyone else had same problem or know the issue?