Shibboleth Developers

1) in my shibboleth2.xml file, I've not got only one SessionInitiator:

<SessionInitiator type="Chaining" Location="/DS" id="DS" relayState="cookie">
	<SessionInitiator type="SAML2" defaultACSIndex="1" 
template="/etc/shibboleth/bindingTemplate.html"/>
        <SessionInitiator type="Shib1" defaultACSIndex="5"/>
                <!-- <SessionInitiator type="ADFS"/> -->
	<SessionInitiator type="SAMLDS" 
URL="https://stc-test11.cis.brown.edu/DS"/>
</SessionInitiator>

2) I'm being successfully redirected tot he DS; here's the url from 
my browser window:

https://stc-test11.cis.brown.edu/DS/?entityID=https%3A%2F%2Fstc-test11.cis.brown.edu%2FShibboleth.sso%2FMetadata&return=http%3A%2F%2Fstc-test11.cis.brown.edu%2FShibboleth.sso%2FDS%3FSAMLDS%3D1%26target%3Dcookie

I'd note that there's an extra slash, added after /DS .....

3) this is now being successfully mapped thru apache, but tomcat is 
barfing with a 404:

The requested resource (/DS/) is not available.

4) my webapps directory does seem to contain DS, however....

[root@stc-test11
 tomcat]# ls -al /usr/local/tomcat/webapps
drwxr-xr-x 10 stc  stc     4096 Dec  7 13:17 .
drwxrwxr-x 11 stc  stc     4096 Dec  4 12:53 ..
drwxr-xr-x  5 stc  stc     4096 Aug 24 19:34 balancer
drwxr-xr-x  5 root root    4096 Dec  7 13:18 DS
-rw-rw-r--  1 stc  stc  3089008 Dec  7 13:17 DS.war
drwxr-xr-x  5 stc  stc     4096 Dec 11 12:27 idp
-rw-r--r--  1 root root 9044343 Dec  5 09:59 idp.war
drwxr-xr-x 21 stc  stc     4096 Nov  9 14:38 jsp-examples
drwxr-xr-x  4 stc  stc     4096 Nov  9 14:38 ROOT
drwxr-xr-x  4 stc  stc     4096 Nov  9 14:38 servlets-examples
drwxr-xr-x 12 stc  stc     4096 Nov  9 14:38 tomcat-docs
drwxr-xr-x  3 stc  stc     4096 Nov  9 14:38 webdav

suggestions?