Level 9 Only Getting Billions of Waves of Sappers

Not quite sure what I have done to get this bug, or how it has now happened twice, but on level 9 it would seem I have completed every objective, but I am not getting any wave other then billions of sappers...

I start with making a 3x3 Garrison. With a 3x3 room filled with traps.
Top down
3 cannons
cannon, bone chiller, cannon
3 cannons
All rampart except the middle roe, so my imps can grab heroes for the prison & torture chamber.

Waves melt against the defenses.

I use replaces dirt so I get nice 5x5 rooms where possible.

After converting every thing, and a fairly quick battle,
I am now some handful hours latter... I am getting billions of sapper bodies piling up at the hero gate, and am unable to complete the level... so... as entertaining as it is to see billions of bodies pile up... I would like to be able to finish the level... >_<