I sounds to me like you have added a field to a table, and now you want to report on it in your report? The reason it not appearing in your field selection list is this.
When you associate a table or query to a report(or form), access build a SQL string associated to the table as it is built at that time. So even though you added a field to the table, the SQL string doesn't show that field as existing. To resolve the problem do this.
1. Open your report
2. Right click on the gray box in the top left corner of the design grid.(It should turn black when you click.
3. Select properties.
4. Click on the data tab
5. You will see the SQL string in the record source field(Don't worry you don't need to edit the string)
6. Click on the record source field
7. Click on the ... button that appears.
8. You should now be in a query design grid.
9. Drag the field from the table to the query grid.
10. Close the query.
11. Check your field selector. The field should now be visible.
HTH.
