Autoinstallation SRX 100

Hi,

I need to configure many SRX 100h2 device at once. I'm thinking to use Autoinstallation. So i created a DHCP and TFTP Server. the dhcp is set to give to each SRX device an IP address. When i plug in the router (the first time) he does not get the ip address. How can in insure that he get one ? or that he's trying to get the ip address ?

dhcp conf :



when i plug another device like a computer or SIP Phone they get their ip address. 

Thanks for help.