SRX 210 Backup interface and load balance

[Nevermore]

Hi;

I have 2 adsl lines. I want to use one of them as backup line. Primary is on fe-0/0/7 Backup link is on : at-1/0/0 interface

I searched kb and found configurations but could not run :

set interfaces fe-0/0/7.0 backup-options interface at-1/0/0.0

error: interface: 'at-1/0/0.0': invalid value

I also tried to configure it from GUI but same problem happened.

I have the latest JunOS on my SRX device.

The second questions is:

Can I load balance these 2 adsl lines?

[mjain]

AFAIK all physical interfaces can be configued with backup-option for Dialer interface (dl0) only & also i dont think we support load blancing.