Send image from c++ server to Android client

I have on my C++ server an image saved as blob in a sqlite database. I take these image from database like this:

        int sizeForThumbnail = sqlite3_column_bytes(sqlStmt, 1);
        char* thumbnail = (char * )sqlite3_column_blob(sqlStmt,1);

After this i send it to the Android phone using a socket connection:

        strcpy(messageToSend,to_string(sizeForThumbnail));
        write(clientDescriptor,messageToSend,strlen(messageToSend));
        write(clientDescriptor,thumbnail,sizeForThumbnail);

On the Android phone i try to get the image like this:

        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        char[] buffer = new char[65536];
        int countForSize = br.read(buffer,0,65536);
        buffer[countForSize] = '\0';
        String size = new String(buffer,0,countForSize);

        InputStream in = socket.getInputStream();
        int sizeInt = Integer.parseInt(size);
        byte[] byteBuffer = new byte[sizeInt];
        int countForBytes = in.read(byteBuffer,0,sizeInt);
        Bitmap bmp = BitmapFactory.decodeByteArray(byteBuffer, 0, byteBuffer.length);
        ImageView photo = (ImageView) findViewById(R.id.imageView);
        photo.setImageBitmap(bitmap);

Now i read exactly how much i send from the c++ server. countForBytes is equal with sizeForThumbnail but decodeByteArray() returns null. What am i doing wrong? After i get the image from database i tried to write thumbnail in a file and save it as jpeg format and it gets the correct image so the retrieval from the database is correct.