why SLA Track 8 isn't applicable to my ISR Router

On a Cisco ISR 4451 I configure SLA Function as follow:

track 8 ip sla 1 reachability
ip sla 1
 icmp-echo 10.1.1.81 source-ip 10.1.1.80
ip sla schedule 1 life forever start-time now

And then I want to apply it to the static route:

ip route 10.2.0.0 255.255.0.0 10.1.1.81 track 8
ip route 10.2.0.0 255.255.0.0 10.1.2.81 10

But this will result in following Static route:

ip route 10.2.0.0 255.255.0.0 10.1.2.81 10

So the first route with track feature isnt applicable, withou track 8 it works and there are two routes. The SLA track Feature works as I can see in the logs:

*Jul 29 07:45:59.735: %TRACK-6-STATE: 8 ip sla 1 reachability Up -> Down
*Jul 29 07:50:54.738: %TRACK-6-STATE: 8 ip sla 1 reachability Down -> Up

So why I cant apply the track 8 to the static route?