I use the code block below to convert a string from UTF-8 to Shift-JIS charset

Dim strU8Title As String
Dim strJTitle As String
Dim rbyteU8Title() As Byte
Dim rbyteJTitle() As Byte
strU8Title = Request.Form.Get("txtMessage")
rbyteU8Title = System.Text.Encoding.UTF8.GetBytes(strU8Title)

rbyteJTitle = System.Text.Encoding.Convert(System.Text.Encoding.UTF8, System.Text.Encoding.GetEncoding("shift-jis"), rbyteU8Title)

strJTitle = System.Text.Encoding.GetEncoding("shift-jis").GetString(rbyteJTitle)

After converting, I display both strU8Title and strJTitle using two <asp:label> , then, switch "character encoding" between UTF-8 and Shift-JIS, but both of them are displayed exactly same.
Did I use wrong function?
Any help would be appreciated.