Protocol static with virtual devices

[kiwi]

Hi everyone,

many months ago I tried to install a route on a virtual device (IPIP, 
GRE, doesn't matter) like this:
protocol static {
   1.2.3.0/24 via "ipip0";
}

It didn't worked out. So I've choosen another non-bird solution. 
Yesterday I tried it again and it still does not work. Now I've tried to 
investigate a bit:
birdc show interfaces:
ipip0 DOWN (index=39)
	PtP Multicast AdminUp LinkUp MTU=16412

Looks like bird don't want to install the route because of the devices 
state (AdminUp, LinkUp but DOWN). "Protocol device" is active (scan time 
10) and birdrestarts also don't help.
bird> show route for 1.2.3.0/24
Network not in table

Any ideas?

Best regards,
Manu