unable to save data to DOM, using dropdown on repeating section and secondary data

[DeMi]

I have created a dropdown which gains its items via a secondary data
source. (MS sql database). The drop down is on a repeating section. The
data source in the DOM is linked correctly to the dropdown.

The problem occurs when I add multiple repeating sections. It seems the
sections after the first are no longer able to save data to the DOM.
Although when I insert items manually to the itemlist in the dropdown,
the functionality works fine.
(if I select something in the dropdown of the first section, all other
sections will change to that value (view). But the value in the DOM,
other then the first section, are empty)

I also add a where statement to the query which is filling the
dropdown.

code to update the dropdown:

var objEmpDS = XDocument.DataAdapters("site_dropdown");
var strSQL = objEmpDS.Command;
var SearchString = getNode("my:form/my:number").text;
objEmpDS.Command = strSQL + " WHERE CUSTOMER_ID = " + SearchString;
objEmpDS.Query();
objEmpDS.Command = strSQL;

I don't see what i'm doing wrong since I only changed the dropdown
items from manual to a secondary source. Again: the form works fine
using manual items in the dropdown.

I hope you guys have a clue what the cause of this problem is.