That java jta extension could not be found, so I have copied it with this command:
# cp /usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre/lib/jta.jar /usr/share/java
Also there were permissions problems, tomcat's directories were owned by tomcat4 group and I have fixed it with this command:
# for f in `find /usr/share/tomcat5/ -follow -group tomcat4`; do chgrp tomcat $f; done
Now tomcat is running, please check it.