problems saving to xml

<i><b>Originally posted by : Chris (ceschrol@unity.ncsu.edu)</b></i><br /><br />Hey. I've been using the Sam's Teach Yourself ASP.NET in 21 days book. There is a section where you load an existing xml file (that is setup with tags that make it act like a bookstore that has individual books). However, when you make a change such as appending another book, it won't let you save back to the original file. It seems to let me save the changes to other files, but it won't let me replace the original. I typed it in word for word how the book has it, so I wondering if it might be a setting in IIS I need to change or something. Any help would be greatly appreciated. <br /><br />xmldoc.load(server.mappath("books.xml"))<br />xmldoc.save(server.mappath("books.xml"))<br /><br />