You code has errors. Please read documentation on how to take care that xml is error free.

You can open log with "O" key or in code with showlog(); There you can see the error that is blocking execution.
try with this code and find this wrong call for buildthumbs:
<action name="autotour">
set(step,1);
oninterrupt(break);
if(step == 1, lookto(360, get(view.vlookat),get(view.fov), smooth(2,2,15), false); inc(step););
if(step == 2, loadscene(YOURSCENE_2, null, MERGE, ZOOMBLEND(1,2) ); inc(step); wait(load); );
if(step == 3, lookto(360, get(view.vlookat),get(view.fov), smooth(2,2,15), false); inc(step););
if(step == 4, loadscene(YOURSCENE_3, null, MERGE, ZOOMBLEND(1,2) ); inc(step); wait(load); );
if(step == 5, lookto(360, get(view.vlookat),get(view.fov), smooth(2,2,15), false); inc(step););
if(step == 6, set(step,1); autotour(););
</action>
also there is error in your startup. it should be:
<action name="startup">
loadscene(YOURSCENE_1, null, MERGE, ZOOMBLEND(1,2)); wait(load); set(idletime,4); set(events.onidle, autotour(););
</action>
If not working send me your project or store somewhere to download to make it run correctly.
regards
Umalo