Drop Down List In 3 Tier Style

hi there , i am trying to populate a drop down list using a 3 tier style
1 will be the class.vb , next webservice.asmx , next is the webform
currently i am having some problems with the coding

<code>
//class1.vb
PublicFunction getBanquetProvider()
cnn.Open
Dim strSql As String = "SELECT DISTINCT Company FROM Banquet"
Dim cmd As New OleDbCommand(strSql, cnn)
Dim da As New OleDbDataAdapter(cmd)
Dim ds As New DataSet
Return da.Fill(ds)
cnn.Close()

//webservice.asmx
<WebMethod()> _
PublicFunction banquetProviderlist()
Dim dl AsNew CalculatorData.Class1
Return (dl.getBanquetProvider())

//webform.aspx
Dim bl AsNew getService.Service1
ddl_provider.DataSource = bl.banquetProviderlist()
ddl_provider.DataBind()
</code>

thanks in advance