Whats the deal with the catcher bag on this unit? I used it for several hours yesterday and it didn't catch anything! I ended up blowing all debris into a pile with BR600 and raking into a tarp. I had the flail blades set to the proper height (Just touching the concrete). The use of the bag on this unit is very important and would really save some time if it would work, if not I cannot believe they would sell a bag for it...judging by the wear on the bag it appears that it had been used prior to my ownership of the unit. Suggestion, ideas or recommendations?