How can I create LRT with session-agent-group as next-hop?

I created lrt:

<?xml version='1.0' encoding='UTF-8'?>

<localRoutes>

<route>

<user type='E164'>8</user>

<next type='regex'>!(^8\d{6}$)!sip:\1@a.b.c.11!</next>

<next type='regex'>!(^8\d{6}$)!sip:\1@a.b.c.12!</next>

<next type='regex'>!(^8\d{6}$)!sip:\1@a.b.c.13!</next>

</route>

</localRoutes>

I have these session-agents in a group with name FAX

so I tried

<?xml version='1.0' encoding='UTF-8'?>

<localRoutes>

<route>

<user type='E164'>8</user>

<next type='regex'>!(^8\d{6}$)!sip:\1@FAX!</next>

and

<?xml version='1.0' encoding='UTF-8'?>

<localRoutes>

<route>

<user type='E164'>8</user>

<next type='regex'>!(^8\d{6}$)!sip:\1@sag:FAX!</next>