Why does damages do not spread on destructible mesh

Hello everyone,

I am facing some problem with the destructible meshes on UE 4.10
I am creating a destructible mesh with a damage threshold of 100 and a I want it to explode on collision with my bullets but I want it to need 2 shots to explode.

So in OnComponentHiy(DestructibleComponent) I apply damage of 50 at the impact point.
Problem is when my bullets hit both the same area of DM, it explodes but if they impact further locations of the same DM, it does not until 2 bullets impact the same area …

81605-applydmg.png

81606-dmsettings.png

So my guess is that the damages do not spread correctly and I am then asking for your help.
I have tried setting a bigger DamageSpread value but it does not affect the behaviour of the DM. I also tried applying point damages or radial damages with a large damage radius but it does not change anything to my problem as well …

I hope some experienced users will be able to help me with that.

Thank you