this is the minimum configuration I've used for the SRX and sometimes this has required a reboot for the successful attainment of an address on the interface.
set interfaces ge-0/0/0 unit 0 family inet dhcp retransmission-attempt 6
set interfaces ge-0/0/0 unit 0 family inet dhcp retransmission-interval 5
set interfaces ge-0/0/0 unit 0 family inet dhcp update-server
set security zones security-zone untrust interfaces ge-0/0/0.0 host-inbound-traffic system-services dhcp