I had this experience in Chapter 8. When I was going through the SDC wizard I could not map the discount percent. When I tried I got the following error.

Cannot map columns of different types.
Column 'DiscountPct' is of type 'System.Decimal' and column 'DiscountPct' is of type 'System.Double'.

I changed the data type in the build script to SmallMoney to match the source table and everything worked fine. Then for fun I changed the script back to use a float and recreated the table and the packages still executed. However If I re-launched the SDC wizard I could not map the Discount percent back up.

hi I thing because when you open the sdc wizard, it checks fort he metadata of the input/output columns and found the inconsistency... if you run it doe not check that and probably it will inject some rounding errors because smallmoney has a different precision rather than float.... [even it seems float is more rpeciese than smoney ]

http://databases.aspfaq.com/database...c-columns.html