Problem selecting item in list box

[aout]

Hello,

I am pretty new to ASP.NET, I hope someone can help me out. I am having problem with list box

I can't seem to get any item selected when the list coming from database, but if I manually add listitem, I could select an item. I dont understand where I get wrong

here's my HTML:

<asp:Listbox id="txtAllLocationID" runat="server" Width="125px"  SelectionMode="Multiple"
	DataValueField="locationID" DataTextField="location" rows="8" EnableViewState="true" Enabled="true">
</asp:Listbox>

and I have a button to add location from this list box, here's my codebehind:

binding listbox to the datasource:

strSQL = "EXEC sp_VM_getVMAlllocation '" & strUsername & "', '" & intVMID & "'"
        objCommand = New SqlClient.SqlCommand(strSQL, objConnection)
        objReader = objCommand.ExecuteReader()
        txtAllLocationID.DataSource = objReader

        txtAllLocationID.DataTextField = "location"
        txtAllLocationID.DataValueField = "locationID"


        txtAllLocationID.DataBind()

        objReader.Close()

and the button click:

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

       Dim LocationItem As ListItem
        For Each LocationItem In txtAllLocationID.Items
            If LocationItem.Selected Then
                strSQL = "EXEC sp_VM_addCurrentLocation '" & strUsername & "', '" & intVMID & "', '" &    LocationItem.Value & "'"
                objCommand = New SqlClient.SqlCommand(strSQL, objConnection)
                objCommand.ExecuteNonQuery()
            End If
        Next
    End Sub

I have been on to this all morning and I am stuck, if someone can help me out it would be great. Thanks in advanced!!!!