Unicode issue

[mprashant]

I have an input table and an output table whose column definitions are already known. All the columns that match are mapped accordingly.The columns that are present in the source database and NOT present in the target, have to be set to Null. I set the derivation field using @NULL for all these columns. Now however I get a mismatch error saying invalid data type for a column called BoxNumber in my target database which is defined as "ntext" in the SQL Server. This column is not present in my source database. I dont understand the problem as the fields are defined as nullable and datastage picks up the SQL type for BoxNumber as NLongVarchar (which suggests it is unicode).Please let me know if you have any inputs