The following code is working properly if connecting with MS Access. But it is throwing error "Must declare the scalar variable "@blob_data", while connecting with SQL Server 2005 Express Edition.

Can anybody tell me the solution?


comm.CommandText = " UPDATE Signature " +
" SET Signature = @blob_data" +
" WHERE AppNumber = '" + appNumber + "' and SignatureType = " + signatureType.ToString();
comm.Parameters.AddWithValue("@blob_data", SqlDbType.VarBinary);
comm.Parameters["@blob_data"].Value = blobData;
comm.ExecuteNonQuery();

Thx. in advance.