Hello,
I think that you can't specify a concrete number of times for the ping.
I suggest you specify a following configuration.
-----------------------------
ip sla 1
icmp-echo 10.10.10.10 source-ip x.x.x.x
timeout 2000
frequency 3
ip sla schedule 1 life forever start-time now
track 1 rtr 1
delay down 10
-----------------------------
It means it waits another 10sec when ping can't reach to the object.
And I recomend that you specify the "sorce-ip" because keep back a flap owing to ping reachs the object going through backup.
HTH,
Tomoyuki