Validate base64 zip xml file by xsd

I need validate base64 zip xml file. Zipped by SharpZipLib.Zip. I create test code for validation, but when run reader.Read() method I have error - System.Xml.XmlException, '.', hexadecimal value 0x00, is an invalid character. Line 1, position 1.

string xsdPath = @"@"c:\Test.xsd"; byte[] byteArray = Convert.FromBase64String(Resources.TestBase64);

using (Stream memInput = new MemoryStream(byteArray))
            using (ZipInputStream input = new ZipInputStream(memInput))
            {
                ZipEntry entry = input.GetNextEntry();

                byte[] newBytes = new byte[entry.Size];

                XmlSchemaSet sc = new XmlSchemaSet();
                StringReader stringReader = new StringReader(File.ReadAllText(xsdPath, Encoding.Default));

                // Add the schema to the collection.
                sc.Add(null, new XmlTextReader(stringReader));

                // Set the validation settings.
                XmlReaderSettings settings = new XmlReaderSettings();
                settings.ValidationType = ValidationType.Schema;
                settings.Schemas = sc;
                settings.CheckCharacters = false;
                settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack);

                MemoryStream streamXml = new MemoryStream(newBytes);
                streamXml.Position = 0;
                StreamReader readerXml = new StreamReader(streamXml, Encoding.UTF8);

                // Create the XmlReader object.
                XmlReader reader = XmlReader.Create(readerXml, settings);

                // Parse the file.  
                while (reader.Read())
                {


   }
}

private static void ValidationCallBack(object sender, ValidationEventArgs e)
        {
            var result = string.Format("Validation Error: {0} -- {1}", e.Message, e.Exception.LineNumber);
        }