yes when in front of the amp..i just had my guitar plugged into it…..—i actually tried both of my h9's  and it worked both times..but whan i put them back into the effects loop.— it stopped working.   i believe that my loop is a series one..—my amp here—  http://www.vhtamp.com/products/the-special-series/special-44-comboi want to keep boht of my h9's in the loop..so this algorithm is basically useless to me in a live situation….so im hoping to figure this out somehow so that it works.

thanks for the help btw

Ok, so you tried just a single H9 in front of the amp, and it was fine.  I'm not clear, however, that you tried a single H9 (with on other pedals chained to it at all) in the effects loop of your amp.  If you haven't, remove your other effects and try that for sure.  That will narrow it down to just one H9 running Undulator.  

VHT's website isn't too clear on what type of effects loop the Series 44 uses.  Any easy way to find out is to turn Kill Dry on (in an algorithm that's working for you).  If Kill Dry is on, and you still hear dry signal, it's a parallel loop, otherwise if you don't hear dry signal, it's a series loop.  I'd need to know to make sure we can set up a test here that duplicates what you are experiencing.