you need to set to active and fast
set interfaces ae1 aggregated-ether-options lacp active
set interfaces ae1 aggregated-ether-options lacp periodic fast
we have a bunch of cisco and junos and I have never had this fail me.
I admit i have never tried it on a RETH but the above should fix you
example
show configuration interfaces ae1 | display set
Jun 07 12:16:09
set interfaces ae1 description "upplink to CORE VIA FEXs rack SA2&3"
set interfaces ae1 aggregated-ether-options minimum-links 1
set interfaces ae1 aggregated-ether-options link-speed 1g
set interfaces ae1 aggregated-ether-options lacp active
set interfaces ae1 aggregated-ether-options lacp periodic fast
set interfaces ae1 unit 0 family ethernet-switching port-mode trunk
set interfaces ae1 unit 0 family ethernet-switching vlan members all
set interfaces ae1 unit 0 family ethernet-switching native-vlan-id 2
set interfaces ae1 unit 0 family ethernet-switching filter output COS-Switch
{master:0}
> show lacp interfaces
Jun 07 12:18:18
Aggregated interface: ae1
LACP state: Role Exp Def Dist Col Syn Aggr Timeout Activity
ge-0/1/0 Actor No No Yes Yes Yes Yes Fast Active
ge-0/1/0 Partner No No Yes Yes Yes Yes Slow Active
ge-0/1/1 Actor No No Yes Yes Yes Yes Fast Active
ge-0/1/1 Partner No No Yes Yes Yes Yes Slow Active
LACP protocol: Receive State Transmit State Mux State
ge-0/1/0 Current Slow periodic Collecting distributing
ge-0/1/1 Current Slow periodic Collecting distributing
show lacp statistics interfaces ae1
Jun 07 12:20:57
Aggregated interface: ae1
LACP Statistics: LACP Rx LACP Tx Unknown Rx Illegal Rx
ge-0/1/0 586616 19727 0 0
ge-0/1/1 586613 19729 0 0
show lacp statistics interfaces ge-0/1/0
Jun 07 12:21:17
Aggregated interface: ae1
LACP Statistics: LACP Rx LACP Tx Unknown Rx Illegal Rx
ge-0/1/0 586636 19727 0 0