Currently pscap drops all capabilities, thus if /proc/<pid>/stat is in some way restricted (3.3? grsec?) its use is limited at best.
This is fixed in 0.6.7 which will be released soon.
libcap-ng-0.7-1.fc17 has been submitted as an update for Fedora 17. https://admin.fedoraproject.org/updates/libcap-ng-0.7-1.fc17
Package libcap-ng-0.7-1.fc17: * should fix your issue, * was pushed to the Fedora 17 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing libcap-ng-0.7-1.fc17' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2012-11057/libcap-ng-0.7-1.fc17 then log in and leave karma (feedback).
libcap-ng-0.7-1.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.