Exchange 2010 DAG Databases logs not clearing by CL

Circular Logging is not clearing or flushing the logs from exchange 2010 DAG Databases

I have three servers  mb01,02,03 and 03 is at DR Site .

when i enable CL at DAG level on one of the Database which is in DAG , it must clear the logs but now it's not working .  Any idea will it clear logs at DAG level with in three servers .

Active, passive , passive .

mb01     02         03

          DAG

CL enabled but not clearing logs . any advise .

highly appreciated .

I.T