Populating Manually A Dropdownlist From Code-behind?

I have code that populates 2 dropdownlist in a gridview. DropStart And DropEnd I want to add time values depending on a few things here's the routine I cal.

Code:

Public Sub GenerateTime(RowIndex As Integer)
Dim ComboStart As New DropDownList
Dim ComboEnd As New DropDownList
Dim ItemList As ListItem
Dim TimeInterval As Integer
Dim IntervalleCalcul As Integer
Dim NombreIntervalles As Integer

[code]....

now this code is called, and runs fine, it goes in the for loop and I see if I trace it that combostart and comboend both have 96 Items in them as expected. hence it did find the controls in the gridview. but when I exit this sub and continue the code by just running the code in the asp.net page the two corresponding dropdown control don't get the values that did get added in the code behind.

In the RowEditing is when I call this routine.

Code:

Private Sub GridDetails_RowEditing(sender As Object, e As System.Web.UI.WebControls.GridViewEditEventArgs) Handles GridDetails.RowEditing

GridDetails.EditIndex = e.NewEditIndex
GridDetails.DataBind()
GenerateTime(GridDetails.EditIndex)
End Sub