Error changing web.config

[pimperiale]

I am trying to add:

<sessionState cookieless="true"/> to my web.config file on my web site but I keep getting a generic runtime error. My web.config is as follows:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.web>
<customErrors mode="Off"/>
<compilation debug="true"/>
</system.web>
</configuration>

It works fine until I add the session line. Unfortunately, at that point I start getting the generic error and cannot troubleshoot. Is there a reason I cannot change the web.config file? It resides in the root directory of my site which is running with .net 1.1.

Any help would be greatly appreciated.