Dacodemasta's puzzle's

[Rene]

It happens when the leftmost of the 7 random barrels is 0.  That barrel will then roll left off the gate at the bottom.  This is why I used an F barrel instead of a 0 under that gate. 
I should note that I used the single stepping in my beta version of Rubicon to track this down.  What are you people waiting for?  You know you want to download it!

I, of course, deliberately introduced this flaw in the solution, so that you guys would be forced to download the new Rubicon for its single stepping capabilities