How to install JSPWiki on a fresh linux vserver?

Downloaded nightly built on 2007-09-30.
Dropped it into webapps of tomcat5.5.
Got this error in tomcat logging:

INFO: ERROR: Failed to create a Wiki engine: access denied
(java.util.PropertyPermission user.dir read)
04.10.2007 11:37:58 org.apache.catalina.core.StandardContext filterStart
SCHWERWIEGEND: Exception starting filter WikiJSPFilter
com.ecyrd.jspwiki.InternalWikiException: No wiki engine, check logs.
    at com.ecyrd.jspwiki.WikiEngine.getInstance(WikiEngine.java:340)

How would you recommend to proceed from here?
- the linux is Debian Edge, just a fresh install
- tomcat5.5 is installed by the default mechanism "apt-get install
tomcat5.5"
- java -version leads to "1.6.0-b105"
- changed jspwiki.properties so that a directory without any access
restrictions is provided, unzipped and dropped the default pages to that
directory
- jspwiki logging configuration is left as delivered but no
/tmp/jspwiki.log is produced