Help populating a combo box in VB

[apgriffiths]

Hi i have a form with two combo boxes, one that specifies a date and one that specifies a location. I also have a third combo box that i want to populate with a corressponding list from a worksheet eg,

Book1
	A	B	C	D
1	Date	LocationName	LocationRef	Route
2	12/05/2008	Aberdeen	1663	0
3	12/05/2008	Aberdeen	1663	101
4	12/05/2008	Aberdeen	1663	102
5	12/05/2008	Aberdeen	1663	103
6	12/05/2008	Aberdeen	1663	104
7	13/05/2008	Aberdeen	1663	105
8	13/05/2008	Aberdeen	1663	106
9	13/05/2008	Aberdeen	1663	107
10	13/05/2008	Aberdeen	1663	108
11	13/05/2008	Aberdeen	1663	109
12	14/05/2008	Aberdeen	1663	110
13	14/05/2008	Aberdeen	1663	111
14	14/05/2008	Aberdeen	1663	112
15	14/05/2008	Aberdeen	1663	208
16	14/05/2008	Aberdeen	1663	422
17	14/05/2008	Aberdeen	1663	581
Sheet1

When i selct the date and location from the first two combo boxes i want the third to only show me the available routes for that location on that day.

I already have the following code for adding items to a lcombo box,<font face=Courier New><SPAN style="color:#00007F">Public</SPAN><SPAN style="color:#00007F">Sub</SPAN> AddItems()<br><SPAN style="color:#00007F">Dim</SPAN> AllCells<SPAN style="color:#00007F">As</SPAN> Range, Cell<SPAN style="color:#00007F">As</SPAN> Range<br><SPAN style="color:#00007F">Dim</SPAN> NoDupes<SPAN style="color:#00007F">As</SPAN><SPAN style="color:#00007F">New</SPAN> Collection<br><br>    <SPAN style="color:#00007F">On</SPAN><SPAN style="color:#00007F">Error</SPAN><SPAN style="color:#00007F">Resume</SPAN><SPAN style="color:#00007F">Next</SPAN><br>    <br>    <SPAN style="color:#00007F">Set</SPAN> AllCells = Sheets("Sheet1").Range("A1:D10")<br>    <br>    <SPAN style="color:#00007F">For</SPAN><SPAN style="color:#00007F">Each</SPAN> Cell<SPAN style="color:#00007F">In</SPAN> AllCells<br>        NoDupes.Add Cell.Value,<SPAN style="color:#00007F">CStr</SPAN>(Cell.Value)<br>    <SPAN style="color:#00007F">Next</SPAN> Cell<br>    <br>    <SPAN style="color:#00007F">For</SPAN><SPAN style="color:#00007F">Each</SPAN> Item<SPAN style="color:#00007F">In</SPAN> NoDupes<br>        cbCombo.AddItem Item<br>    <SPAN style="color:#00007F">Next</SPAN> Item<br>    <br><SPAN style="color:#00007F">End</SPAN><SPAN style="color:#00007F">Sub</SPAN></FONT>

How do i manage to just pick out the selected date and location??