Juniper SRX 345 HA with Flexible Ethernet Services Encapsulation

Hi All

I have configured a pair of Juniper SRX 345 in HA. All is well, except I am unable to configure Flexible Ethernet Services under the RETH main interface. I would like to configure a mixture technologies such as VPLS, MPLS and normal layer 3 ethernet. Running version 15.X

Any suggestions?

Thanks