Just by looking at this screen it looks like you didn't kill any ground targets. In order to get a closterman, you need to kill 7 planes AND at least 15 ground targets. If you get a closterman you would also get a destroyer.
Edit, if you show the results of the team battle screen we could verify the amount of planes killed and ground targets destroyed.
Edited by Psicko23, 10 May 2017 - 02:15 AM.