<asp:TemplateField HeaderText="Negativita" >
   <ItemTemplate>
      <asp:Label ID="Label1" runat="server" Text='<%# Eval("NegativitaTecniche") %>' BackColor='<%# ((int)Eval("Negativita") > 0)? Red : Green %>'></asp:Label>
   </ItemTemplate>
</asp:TemplateField>

        public Color GetColor(int count)
        {
            if (count > 0)
                return Color.Red;
            else
                return Color.White;
        }

<asp:Label ID="Label6" runat="server" Text='<%# Bind("NegativitaTecniche")  %>' 
BackColor='<%# GetColor(Bind("NegativitaTecniche"))  %>'></asp:Label>

public Color GetColor(int count)
{
if (count > 0)
  return Color.Red;
else
  return Color.White;
}

<asp:Label ID="Label6" runat="server" Text='<%# Bind("NegativitaTecniche") %>'
BackColor='<%# 

GetColor( (int) Bind("NegativitaTecniche")) 

%>'></asp:Label>