I made a change to the database and updated the data flow task accordingly.
The changes to the database were dropped.
The next time I looked at the data flow task I saw that the fields that I had created were no longer available for input or output.
The fields could be seen in the automatically generated XML code.
Once the package was saved the fields were removed from the XML code too.
Please can someone explain if there is wat to stop the XML code being updated should the database schema change.