Remove the link /usr/share/bdb/db.jar before installation, if it exists.
Check if a version of ant below 1.5.4 exists on the system by running the following command:
rpm -qa | grep ant
The ant version 1.5.2 interferes with portal configuration. If an earlier version of ant is found installed, remove it by running the following command:
rpm -e ant-1.5.2-23 ant-libs-1.5.2-23