Dynamic Drop Downs In VB 2008?

I have an application which is using a set of three combo boxes. I have managed to populate each drop down depending on the selected value of the previous one The only problem is that, since the data is coming the database two selected values from the first combo box may have two different number of items in the database. so the second combobox should be populated with such data each time the selectedIndex_changed nethod of the first combobox is invoked

if for example, the first combo box's first item has 10 corresponding items in the second combo box and a first combo box's second item has three corresponding items in the second combo box, selecting the second item after selecting the first item will lead to second combobox showing the three items and seven empty entries trailing after the three.

What I want is to have the second combobox loaded with three items exactly when the second item in the first combo box has three items in the database

here is an example

Private Sub cboAccountGroup_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboAccountGroup.SelectedIndexChanged
If mblnAccountGroupFirstLoad = True Then
Exit Sub

[Code]......