What error are you getting?
Save your mpx file in this way.
FileStream fileStream = new FileStream(filename, FileMode.OpenOrCreate, FileAccess.Write);
//file.Write(fileStream, Encoding.GetEncoding(1252));
file.Write(fileStream, Encoding.Default);
fileStream.Close();
Many Thanks and Kind Regards,
Shakeel Faiz
Support Engineer
Aspose Tyumen Team