Zyltarion

Decided to try out this mod today and used the Video tutorial to go step by step over how to install it. However when I try to run the Combined Operations then I get the error message that Arma II can't open the Dayz.pbo file, tried starting from scratch aswell as restarting both Steam and the computer itself to see if that would work, but no avail. Anyone have any suggestions on the cause and how to fix this issue?