R12.1.3 Concurrent Manager: Buttons greyed out on scheduled requests

Have you applied a recent R12.1.3 patch?  If you have, then your version of FNDRSRUN may have a bug in it and the article "Options Button Is Greyed Out For Future Scheduled Request Sets" found in My Oracle Support from note ID 1988337.1 tells you what patch caused this and which one resolves the issue.