Dragoon Job Quest Problem

[Causality]

You need to complete the Main Scenario quest line "Sylph Management" Before you can get your job quest. (They made this Change in patch 2.41 Priorly there was no main scenario requirement ) So you have to get through that Sylph part first its around level 24 quest requirement and will have you do a dungeon called The Thousand Maws of Toto-rak.

Level 30 job quest requirements have been adjusted as follows:
Before:
Players must reach level 30 with the job’s associated class.
After:
Players must reach level 30 with the job’s associated class, and have completed the main scenario quest "Sylph-management."