Dnsmasq as dhcpv6: failed to bind DHCPv6 server socket

LEDE Reboot SNAPSHOT r4744-cdb494fdc2 / LuCI Master (git-17.234.69785-72b90c0)
dnsmasq-full 2.77-9

To distribute a IPv6 address range, i found this for the /etc/dnsmasq.conf. Without it dhcpv6 addresses are only appear by slaac.

dhcp-range for ipv6

dhcp-range=::32,::96
dhcp-option=option6:dns-server,[::]

But it fails to start with this options.
Fri Sep 1 15:25:43 2017 daemon.crit dnsmasq[31747]: failed to bind DHCPv6 server socket: Address in use
Fri Sep 1 15:25:43 2017 daemon.crit dnsmasq[31747]: FAILED to start up

Do someone have dnsmasq running for IPv4 and IPv6?