Problem caching with Apache 2.2 mod_proxy

Hello,
I am trying to configure mod_proxy on Apache 2.2.
(HOWTO on:
http://www.zms-publishing.com/support/content/e732/e736/e947/e1762/index_ger.html)

The Apache could not handle the following code from the HOWTO:
<IfModule mod_proxy.c>
    ProxyRequests Off
    ProxyVia On
    CacheRoot "/var/cache/httpd"
    CacheSize 100000 
    CacheGcInterval 4
    CacheMaxExpire 10
    CacheLastModifiedFactor 0.1
    CacheDefaultExpire 8
   # NoCache  domain1 domain2  
</IfModule>

So I rewrote it to:

<IfModule mod_proxy.c>
	<IfModule mod_cache.c>
		ProxyRequests Off
		ProxyVia On
		<IfModule mod_disk_cache.c>
			CacheRoot "/pathtomycachefolder/cache"
			CacheEnable disk /
		</IfModule>
	</IfModule>
</IfModule>

The creation of the Cache-Files works fine, but on every Request,
Apache creates new Cache-Files, even though pages are not expired...
Any tips, what I missed?
Thanks in advance.