No DHCP on Guest VLAN

Hope someone can help. We have setup FortiNAC and when the device is moved from the registration vlan to the guest vlan, the device does not get an IP from DHCP. I have verified all the config and I cannot see any issues. Does anyone have any suggestions on what might be the problem? I already created a ticket for this, however once the device is moved to the Guest vlan, I am told at that point it is network related and not NAC related.