my voice vlan can not recieve ip from microsoft dhcp server

[salar]

hi
i am itman
i have local net work
my switches : cisco
my ip phone : yealink t19p E2
my dhcp server : windows server 2008R2
config:
vlan 10 name data
vlan 50 name voice

interface vlan 10
ip address 192.168.10.0/24
ip helper address 192.168.100.100

interface vlan 50
ip address 192.168.50.0/24
ip helper address 192.168.100.100


interface gi 0/5
switchport access vlan 10
switchport voice vlan 50
----------------------

my pc recieve ip on range 10.0/24

but my ip phone not recieve ip on range 50.0/24

please help me (about dhcp option on microsoft windows server or other soloution)