I can't recall whether DE (or at least your model) uses a hop arm with a captive nub. If you are getting no hop really at all, there may be a possibility that, in the process of changing the bucking, a non captive nub had dropped out of the hop chamber entirely, and become lost. Possibly able to be checked by removing the hop chamber, holding it upside down, and applying hop to see if the nub moves into view. If it is missing, and the hop arm really can't be removed, then you might be lucky enough to be able to place the nub back into position with the hop unit upside down, and hop fully off - and slide the nub into position via the main body. Or you could install the original bucking back in assuming you haven’t damaged it when you removed it, check the range, to verify that loss of the nub isn't the issue
Of course, the other possibility is that the process of changing the bucking, and maybe the bucking itself, has messed with your air seal - i.e. the nozzle from your gearbox isn't playing nicely with the lips of your bucking, and you are losing a lot of air (and therefore power) this way. When you are sure the gun is unloaded, turn it upside down and without a magazine in place, place a small bit of tissue over the bb feed tube part of your hop unit. If the tissue is dramatically blown about (and not just from vibration) when you fire the rifle, that would start to indicate that this is the case.
You can either try other buckings (not all buckings are compatible with all hop units/nozzle lengths), or try a cheap ZCI hop unit in the gun which appear reasonably universally adequate. The 4uantum buckings seem reasonably well regarded, so they should be doing the business if there isn't a compatibility issue (or you haven’t lost the nub!)
its a cheap nuprol bocca one and the end bore was offset tearing up my bbs.. 
