Sponge not working?

I got on Skygrid one day and found that my base had a hole in it, I couldn't punch the cows from my cow spawner, I couldn't open my chests, my anvil was gone, a bookshelf was missing, and my crafting table and furnaces weren't working. If I stood above my enchant table and jumped, it would say "Leaving Shockwave9647's area" and if I was anywhere below that it would say tat I was entering his area. This led me to believe someone named Shockwave9647 had taken over my base some how. This wouldn't have been weird, except I had a sponge. I know the sponge was working before because I'd seen it in action. When I tracked down an Admin he/she managed to fix it, but when I opened my chests I had lost everything (which was a lot). This included my diamond hoe, axe, and sword, which the Admin replaced for me, my diamond helmet, diamond boots, two ocelot spawn eggs, various other spawn eggs, and my various materials, which the Admin didn't replace. I don't blame the Admin for not replacing everything, since I hadn't been on in a week i couldn't remember what was in my chests on the spot, so I couldn't tell him/her what I had lost. I looked up this Shockwave guy on the website, and he's some 13 year old. I probably won't be coming back to the server because a 13 year old managed to bypass the security (and who's to stop another one from doing the same), but I just wanted to ask if any of you guys know why my sponge wouldn't work.