multiple .htaccess files

I have an .htaccess file in my root directory which performs some automatic redirects and has my custom error pages. I want to add a second .htaccess file in a sub-directory to require a log/passwd protection. When i put this second .htaccess file in the sub-directory, instead of getting the log/passwd box up when i try to access a page within that sub-directory i just get an error. I know the code in my htaccess file is correct as when i delete the .htaccess file in my root, the log/passwd works perfectly. The first htaccess has no code in it to do with authorisation and therefore i dont understand why it is blocking the log/pass in the sub-directory. Is there some sort of command i need to place in the first file to allow the second one to be read correctly ? any ideas ? thanks