getting "karnel Error " when script try to disable interface?

Hello ,
I have a script that cahnge between APN ,
something it’s working just fine
but sometimes he won’t disable the ppp-client “freeze” the system ,then reboot and say :

10:06:32 system,error,critical System rebooted because of kernel failure
10:06:32 system,error,critical router was rebooted without proper shutdown

This is the script:(nothing special)

:global SIM;
:if ([ping 8.8.8.8 count=5] = 0) do={:log warning "No ping"; :if ($SIM = 1) do={:set SIM 2;/interface disable SIM1; /system leds set [find where leds=user-led] disabled=yes;:delay 5;/system script run Reset} else={:if ($SIM = 2) do={:set SIM 1;/interface disable SIM1;/system leds set [find where leds=user-led] disabled=no;:delay 5;/system script run Reset}}} else={:log warning "Ping OK"};

It get stuck before running “Reset” script…

any idea why?

using RB411 V6.32.2 (also try it on V6.35rc42)

I have send to support - waiting for their replay