Hello Savra,
I looked at your site again and even created a new installation for you. The old and new installation have the same problem that I mentioned in an earlier post.
If you go to Extensions > Extensions Manager > Warnings tab You'll see that you have a warning. This would prevent things from uploading and may be the cause of your problem. Let's get that fixed then look at it again.
You also get this warning.
The PHP allow_url_fopen setting is disabled. This setting must be enabled for the updater to work.
I thought you had solved the php.ini problems but it looks like they were never addressed. Or at least whatever fix was made does not apply to the subdirectory. Perhaps you need to ask the host to restart apache to activate the changes.
I did a new installation today on my test servers with the same package that I used on your server. There are no problems there and that install works perfectly.
I think you need to talk to your webhost and find out why you are getting the php warning and ask them to fix it. I removed my installation and your original installation is exactly as you left it.
Also I can't determine which version TravelBook you are using. It is not registered with Joomla and does not show up in the plugin directory. You should double check and make sure you are using the correct version.
Sincerely,
Ed