Reign of the Undead - Revolution

Hey guys 
 Hope all is fine 
I have a small problem here I was once chased by wave 18zombies and did not die but my challenge is still 0 what happened

The only unclosed thread without reply(

For victime challenge , firstly you have to be target , and when you are target you have to stay alive if you die you don t have +1 for challenge.
And if aren't target but you suruvive during the wave you don't have + 1 

Imo

Ya I did not die when I was chased