Combox & Textbox populate.

I have some problems with  Combobox fields populate. I have a table ItemCode with 5 fields.
The fieldnames are : itemid              integer
                                 itemcode          char         3
                                 descrip             char         40
                                 fcamt                numeric    10,2
                                 rmamt              numeric    10,2
 Records are as such.
           itemid      itemcode    Descrip                    fcamt      rmamt  
             1            001            Freight                   20.00      80.00
             2            002            Documentation       15.00      60.00
             3            003            Break Bulk               30.00    120.00
             4            004            Terminal                  5.00        30.00
and so on.....


My problem is this :

I  have a form tcbofrm with a combobox and a textbox. The combobox rowsource = ItemCode.itemcode, rowtype = 6
I have a text box "txtdescrip" with rowsource = ItemCode.Descrip, rowtype = 6.

When I select itemcode 003, It is display onto the combox as "003" and I expect the text box to display "Break Bulk"
but instead it display "Freight" which is the first record descrip field. So whenever I update the comboxbox, the textbox is
not being update with teh same record fields of the combox list.

How do I make it to also to populate the textbox as "Break Bulk", whenever I select in the combox "003" for itemcode ?
In other words, whatver record select but with the fields of the same record to populate for the combox and textbox ?


Louis