Stored Procedure To Update Ntext Value In SQL

Hi

My SP to update a value type ntext don't work,  ALTER PROCEDURE UpdateMultiContentFullDescriptionByID
(@ContentID int,
@FullDescription ntext)
AS
UPDATE MultifunctionalContent
SET FullDescription = @FullDescription
WHERE ContentID = @ContentID
RETURNPublic Sub UpdateMultiContentFullDescriptionByID(ByVal ContentID As String, ByVal FullDescription As String)
' Create Instance of Connection and Command Object
Dim myConnection As SqlConnection = New SqlConnection(Const.ConnectionString)
Dim myCommand As SqlCommand = New SqlCommand("UpdateMultiContentFullDescriptionByID", myConnection)
' Mark the Command as a SPROC
myCommand.CommandType = CommandType.StoredProcedure

' Add an input parameter and supply a value for it
myCommand.Parameters.Add("@ContentID", SqlDbType.Int, 4)
myCommand.Parameters("@ContentID").Value = ContentID

' Add an input parameter and supply a value for it
myCommand.Parameters.Add("@FullDescription", SqlDbType.NText, 8000)
myCommand.Parameters("@FullDescription").Value = FullDescription

' Open the connection and execute the Command
myConnection.Open()
myCommand.ExecuteNonQuery()
myConnection.Close()
End Sub Then how to ...