Reliable Static Routing with IP SLA

Hi Rene,
Fantastic article. This is the senerio I am trying. I have a site that is using a primary link as MPLS and a secondary backup link as VPN (IPsec site-to-site). Due to some erformance issues I would like to change the primary as the VPN and keep the MPLS as the backup. In my case I have a Fortigate Firewall at one site where the MPLS and VPN links terminate and at my head office I have a Core switch where the MPLS terminates and another fortigate where the VPN terminates. I have decreased the Administrative distance on the Fortigates to 18 so that it is lower than BGP 20. Now the VPN is the primary link but when I simulate a outage to the VPN the track routes are still in place hence the link never really fails over to the MPLS. Any pointers would be greatly appreciated.