DataGrid not updating.

<asp:DataGrid ID="dgItems" runat="server" DataSourceID="edsItems" 
            EnableViewState="False" AutoGenerateColumns="False" BackColor="White" 
            BorderColor="#3366CC" BorderStyle="None" BorderWidth="1px" CellPadding="4" >
          <Columns>
              <asp:BoundColumn DataField="Name" HeaderText="Name"></asp:BoundColumn>
              <asp:BoundColumn DataField="Perc" HeaderText="Perc"></asp:BoundColumn>
              <asp:TemplateColumn >
                <HeaderTemplate>
                  <asp:Label ID="lb" runat="server" Text="Dose Type" />
                </HeaderTemplate>
                <ItemTemplate>
                  <asp:Label ID="lbOne" runat="server" Text='<%# Bind("amounts_tb.field1")%>' />
                </ItemTemplate>
              </asp:TemplateColumn>
              <asp:BoundColumn DataField="AmountSupplied" HeaderText="Amount Supplied"></asp:BoundColumn>
              <asp:BoundColumn DataField="VolumeSupplied" HeaderText="Volume Supplied"></asp:BoundColumn>
              <asp:BoundColumn DataField="Max" HeaderText="Max" ></asp:BoundColumn>
              <asp:TemplateColumn >
                <HeaderTemplate>
                  <asp:Label ID="lbAmt" runat="server" Text="Amount" />
                </HeaderTemplate>
                <ItemTemplate>
                  <asp:Label ID="amt" runat="server"  />
                </ItemTemplate>
                </asp:TemplateColumn> 
                <asp:TemplateColumn >
                <HeaderTemplate>
                  <asp:Label ID="lbVol" runat="server" Text="Volume" />
                </HeaderTemplate>
                <ItemTemplate>
                  <asp:Label ID="vol" runat="server"  />
                </ItemTemplate>
                </asp:TemplateColumn> 
          </Columns>
          <FooterStyle BackColor="#99CCCC" ForeColor="#003399" />
          <HeaderStyle BackColor="#003399" Font-Bold="True" ForeColor="#CCCCFF" />
          <ItemStyle BackColor="White" ForeColor="#003399" />
          <PagerStyle BackColor="#99CCCC" ForeColor="#003399" HorizontalAlign="Left" 
              Mode="NumericPages" />
          <SelectedItemStyle BackColor="#009999" Font-Bold="True" ForeColor="#CCFF99" />
      </asp:DataGrid>

Try
      Dim kg As Double
      If Double.TryParse(tbVariable.Text, kg) Then
        For row As Integer = 0 To dgItems.Items.Count - 1
          Dim one, amt, max, amts, vols As Double
          one = CDbl(dgItems.Items(row).Cells(1).Text)
          amts = CDbl(dgItems.Items(row).Cells(3).Text)
          vols = CDbl(dgItems.Items(row).Cells(4).Text)
          max = CDbl(dgItems.Items(row).Cells(5).Text)
          amt = one * kg
          If amt > max Then amt = max
          Dim lbAmt As Label = TryCast(dgItems.Items(row).Cells(6).FindControl("amt"), Label)
          Dim lbVol As Label = TryCast(dgItems.Items(row).Cells(7).FindControl("vol"), Label)
          If Not lbAmt Is Nothing Then lbAmt.Text = Amount(amt, max)
          If Not lbVol Is Nothing Then lbVol.Text = Volume(amt, amts, vols)
        Next
      End If
Catch ex As Exception
      Response.Write(ex.Message)
End Try