SRX to Two ISP failover configuration

Good evening 

We have the following setup:

SRX HA Cluster 1500

Site A:                                              HQ:

SRX Node 0 ----> ISP 1---->MX-104 primary 

SRX Node 1 ----> ISP2------MX-104 backup

Site A have two IPSEC tunnels st0.0 and st0.1. st0.0 connect to MX-104 primary and st0.1 will connect to the MX-14 backup router. 

Site A: ISP1 is the primary link and ISP2 is the backup link to be use ONLY if the primary ISP1 fail. 

The site is currently using static routes on a Cisco router. We bought the SRX 1500 to replace the Cisco router currently in the Site A. 

I am currently testing the SRX-1500 in the lab and using two additional SRXs to simluate the MX. The currently MX-104 are in production. 

Site A have the following static routes:

set routing-options static route 0.0.0.0/0 next-hop 137.52.47.2
set routing-options static route 0.0.0.0/0 qualified-next-hop 137.52.79.2 preference 10
set routing-options static route 1.1.1.1/32 next-hop st0.0
set routing-options static route 137.52.70.0/24 next-hop 137.52.47.2
set routing-options static route 2.2.2.2/32 next-hop st0.1
set routing-options static route 137.52.0.0/24 next-hop st0.0

RPM configured:

set services rpm probe example test test-name target address 137.52.47.2
set services rpm probe example test test-name probe-count 3
set services rpm probe example test test-name probe-interval 15
set services rpm probe example test test-name test-interval 10
set services rpm probe example test test-name thresholds successive-loss 3
set services rpm probe example test test-name thresholds total-loss 3
set services rpm probe example test test-name destination-interface ge-0/0/0.0
set services rpm probe example test test-name hardware-timestamp
set services rpm probe example test test-name next-hop 137.52.47.2

set services ip-monitoring policy test match rpm-probe example
set services ip-monitoring policy test then preferred-route route 137.52.0.0/24 next-hop st0.1
set services ip-monitoring policy test then preferred-route route 10.0.0.0/8 next-hop st0.1

The problem i am having is that when i simulate failure in ISP1 uplink interface (manually disable the uplink interface). The st0 tunnels stay up and do not failover to st0.1  

No failure in ISP1 routing table:

root@sanjuan-fw01-n0> show route protocol static            

inet.0: 31 destinations, 32 routes (31 active, 0 holddown, 0 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

0.0.0.0/0          *[Static/5] 00:00:30
                    > to 137.52.47.2 via ge-0/0/0.0
                    [Static/10] 1d 01:31:26> to 137.52.79.2 via ge-7/0/0.0
1.1.1.1/32         *[Static/5] 00:00:27> via st0.0
2.2.2.2/32         *[Static/5] 04:49:40> via st0.1
137.52.0.0/24      *[Static/5] 00:00:27> via st0.0
137.52.70.0/24     *[Static/5] 00:00:30> to 137.52.47.2 via ge-0/0/0.0

ISP1 Fail:

root@sanjuan-fw01-n0> show route protocol static    

inet.0: 30 destinations, 31 routes (30 active, 0 holddown, 0 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

0.0.0.0/0          *[Static/10] 1d 01:33:35
                    > to 137.52.79.2 via ge-7/0/0.0
1.1.1.1/32         *[Static/5] 00:02:36> via st0.0
2.2.2.2/32         *[Static/5] 04:51:49> via st0.1
10.0.0.0/8         *[Static/1] 00:00:07> via st0.1
137.52.0.0/24      *[Static/1] 00:00:07> via st0.1
                    [Static/5] 00:02:36> via st0.0

root@sanjuan-fw01-n0> show services ip-monitoring status 

Policy - test (Status: FAIL)
  RPM Probes:
    Probe name             Test Name       Address          Status   
    ---------------------- --------------- ---------------- ---------
    example                test-name       137.52.47.2      FAIL     
  Route-Action:
    route-instance    route             next-hop         state
    ----------------- ----------------- ---------------- ------------- 
    inet.0            137.52.0.0/24     st0.1            APPLIED      
    inet.0            10.0.0.0/8        st0.1            APPLIED   

root@sanjuan-fw01-n0> show security ipsec security-associations 
node0:
--------------------------------------------------------------------------
  Total active tunnels: 1
  ID    Algorithm       SPI      Life:sec/kb  Mon lsys Port  Gateway   <131074 ESP:aes-cbc-128/sha1 4eba255b 3095/ unlim U root 500 137.52.79.2     >131074 ESP:aes-cbc-128/sha1 4e50a5eb 3095/ unlim U root 500 137.52.79.2  

The problem i am facing is that the st0.0 static routes are not being removed when the st0.0 goes down. 

I need to make sure the failover occur when the ISP1 port goes down in addition when there is no internet connection.