problem with combo boxes on subform

I have a subform with 7 columns bound to a table.  Two of the columns in the subform, named cmbStock and cmbBin, are combo boxes for selecting values.  The Row sources for each combo box are as follows:

cmbStock -  SELECT [Stock Locations].[Stockroom] FROM [Stock Locations] ORDER BY [Stockroom];
cmbBin -  SELECT [StockLocation_Bins_B].[Bin], [StockLocation_Bins_B].[InventoryLocationDescription] FROM StockLocation_Bins_B ORDER BY [Bin];

StockLocation_Bins_B is a select query.  

In the On Current Event for the subform I have the following code which dynamically changes query StockLocation_Bins_B based upon the value in cmbStock and then requerys cmbBin.  Although the query does get changed correctly the values in cmbBin do not change.  What am I doing wrong?

Dim QDFDynamic As QueryDef
    Dim SQL01 As String
    Dim SQL02 As String
    Dim SQL03 As String
    Dim SQL04 As String
   
   Set QDFDynamic = CurrentDb.QueryDefs("StockLocation_Bins_B")
   SQL01 = "SELECT dbo_FS_InventoryLocation.Bin, dbo_FS_InventoryLocation.InventoryLocationDescription "
    SQL02 = "FROM dbo_FS_InventoryLocation "
    SQL03 = "WHERE (((dbo_FS_InventoryLocation.Stockroom)='" & cmbStock & "')) "
    SQL04 = "ORDER BY dbo_FS_InventoryLocation.Bin;"
    QDFDynamic.SQL = SQL01 & SQL02 & SQL03 & SQL04
    QDFDynamic.Close
   
    cmbBin.Requery