This campaign have several flaws that may affect on gameplay. The major issue there is the lack of the map's stringtables -- meaning that the host server will crash when the player joins in. This is actually affected on some dedicated servers, such as from this group. There's also some of the ERROR props such as this one. This co-op game needs a major remedial fix on mapping problem.

On a side note, how can we put those 6 gas cans on the second chapter? Just obvious.