Error msg when I put a new comment for a book page

Thank you for the responses, positive or negetive. Now coming to the point.
I have uploaded all files in the sites/all/theme folder and still when I change the theme to any other through the appearance, it still does not let any change visible on the screen. So I go back to my default Bartik one and see that all settings are perfect in the appearance page, but no effect seen on the website.Is there a settings file for theme as well where I can see? Also I read in an article that the variable table for themes will be having the information on theme settings, but when I go to phpMyAdmin to see the database, it does not allow me to see any variable table as its not editable. How to view tables in Editable mode.

I think the problem was the directory in which I was storing the 'sites' file. It was not directly under the public_html but was under three levels in a new directory folder that I had made to put my uploaded files from backup. Then I downloaded another theme and made it as default and saw all the files were made in sites folder directly under public_html file. So thank you for the responses and I hope this problem could have been solved by changing the placement of the 'sites' file and its subfolders.

Problem of theme solved!

Now I am facing another problem. I downloaded modules like Field validation, entity reference and its required modules. Then I created a rule to validate but realised that it would not work. hence deleted the rule. but since I had saved the configuration, the error keeps coming up telling me the source of error is in the line number so n so in file public_html/includes/entity.inc
Now when I see this file, the error source is not seen as it calls the variables to load the data and not the fields label directly, i don't know what to delete? I disabled all validation modules in the modules menu.
Will I have to look up in some database table for the error or something else?

Hi,
I use the Book module for my content. I see that my site has a login user name and password option as I enabled the open ID module in the modules. But it still allows users to access the contents of the website without logging in. Also in spite of making all content permission limited to the given users and administrator, it has view and edit option on top of some book pages that is accessible without logging in. Through edit it allows the title to be changed and saved. I don't want every reader to alter my site. Where did I miss out?Please I want someone to look into this too.
Thank you in advance.

I solved this problem of login by taking away all permissions of anonymous users and thank god now it works and the site is not visible to all except those who will login.

How to make a comment get connected to a book page content so that whenever somebody writes about that article, the posted comments can be read by others too when they open this book page to view? I see the "Add comments" page just below the main content area and I want it to be linked to the article and be visible. How can this be achieved? The Add comments page is not created by me but is available through some code I guess so don't even know where to configure it from.

Notice: Undefined property: stdClass::$book in template_preprocess_i18n_book_navigation() (line 379 of /home/admin4321/public_html/sites/all/modules/i18n_book_navigation/i18n_book_navigation.

What does the above error message do and how can it be overcomed?