Failed to enable constraints

System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
at System.Data.DataTable.EnableConstraints()
at System.Data.DataTable.set_EnforceConstraints(Boolean value)
at System.Data.DataTable.EndLoadData()

For Tracking Project,need to change Spread.Data project SpreadDb.xsd, for some column's length of TABLE NewsLetterSystem_Subscriber is exceed