Combobox filled using datatable fails

I am trying to get a list of items to fill in a combobox.

I call a function and expect a return list.... what is wrong with my code?  

cbbae.DataSource = employeelist("sales")
 
 
 
    Public Shared Function employeelist(ByVal Dept As String)
 
        Dim cbb As ComboBox = New ComboBox
        Dim dt As DataTable = New DataTable
        Using conn As New SqlConnection(myconnectionstring)
            Using cmd As New SqlCommand("APP_GetEmployeeList", conn)
                cmd.CommandType = CommandType.StoredProcedure
                cmd.Parameters.AddWithValue("@department", Dept)
 
 
                Using da As New SqlDataAdapter(cmd)
 
 
                    da.Fill(dt)
                    With cbb
                        .DataSource = dt
                        .DisplayMember = "repcode"
                    End With
 
 
                End Using
            End Using
        End Using
 
        Return cbb.DisplayMember
 
    End Function

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