Among the options:
1) ensure that column headings in the worksheet range match the field
names in the table you're importing to.
2) temporarily link or import the worksheet (using the wizard) and then
use an append query to map fields and do any necessary type conversions.
3) forget about the wizard and write the SQL statement for an append
query to move the data from the worksheet into your table. The syntax is
like this:
With column headings, import from specified range:
INSERT INTO MyTable
SELECT Column1 As Field1, Column2 As Field3, Column3 As Field2
FROM [Excel 8.0;HDR=Yes;database=C:\MyWorkbook.xls;].[Sheet1$A1:C999]
;
Without column headings, import from named range
INSERT INTO MyExistingTable
SELECT F1 As Field1, F2 As Field3, F3 As Field2
FROM [Excel 8.0;HDR=No;database=C:\MyWorkbook.xls;].[MyRange]
;