localize the label to german language when the button clicked

hi,
i want to localize the Welcome message(which is created in the code behind ) to German language. I have created the App_LocalResources folder and
Test.aspx.de-DE.resx ,Test.aspx.resx files. i have specified the name and value in both the files. here is the code


<asp:TextBox ID="txtName" runat="server" Width="87px"></asp:TextBox>
<asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit_Click" Text="Submit" meta:resourcekey="lblMaster" />


if (Session["UserName"] != null)
{

Label lblMaster = (Label)Master.FindControl("lblMaster");
lblMaster.Text = "Welcome " + (Session["UserName"]).ToString();
}

its not displaying the welcome message in the German language.

Thanks for the help