Combo box binding problem

Hi - i wonder if anyone has a solution or workaround the following problem:
I'm using binding method for navigating thro a DB. (In this example the employees table of the access NWindDB). This table has a field ReportsTo which is th ID of another employee - the boss. On my employee form i've got a combo 'ReportsTo' which is populated with the employees.
I've modified some fields in the NWind employees: as follows
(The last column is the result i get when i step thro the table:

ID Name : ReportsTo :
1 Nancy Davolio : : My result= Nancy Davolio
2 Andrew Fuller : : My result= OK
3 Janet leverling : Fuller,Andrew : My result= OK
4 Margeret Peacock : Fuller,Andrew : My result=OK
5 Steven Buchanan : : My result= Nancy Devolio
6 Michael Suyama : Buchanan,Steve :My result= OK
7 Robert King : Buchanan,Steve :My result= OK
8 Laura Callahan: : My result= Nancy Davolio
9 Anne dobworth : Buchanan,Steve :My result OK


Problem 2: I need a method /solution to set the reportsTo field to nothing for a employee who is the boss - and the dataset reflects the change. I've tried combobox.text="" . As far as the DS is concerned there is no change. Any idea