force existing php site into wordpress

Hi all:

I’m using trying to get some existing php into wp and having a bit of difficulty. Essentially, I don’t need to do anything other than take the existing php code that I have and add the wp theme header and footer to it (so that all our pages have a consistent look). I’ve managed to get the initial page of the form that I am moving over to look exactly like the rest of the theme (I just made it a template and it worked) however when I attempt to do this to the other pages they load as per usual – no header or footer or colors from the theme appear. As soon as I add the get_header or get_footer to a page it just renders completely white – no content whatsoever. Thoughts on this? I’m using responsive theme and attempting to add the open source library assignment calculator into my site.