I have used following code and it works fine for me
using System.Globalization;
using System.ComponentModel;
using System.Threading;
.......
.......
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Thread.CurrentThread.CurrentUICulture = new CultureInfo(DDLLang.SelectedValue);
ComponentResourceManager resource = new ComponentResourceManager(typeof(Default));
resource.ApplyResources(LblName, "LblName");
LblName.ID = "LblName";
Response.Write(resource.GetString("strMsg",CultureInfo.CurrentUICulture)??resource.GetString("strMsg"));
In above code LblName is a Label and StrMsg a simple string.
In resource file I will write like this:
Name Value
Lbl.Name labelname................
StrMsg anycustom msg............