Don't worry, Kronos, your applet worked fine ( at least for me ) at your www.besli.de
site. opiop65 just meant that you embedded it uncorrectly in your first message here.
Unfortunately, I'm afraid I can't do much to help you to correct it.
And concerning your game, well, I found it original and quite interesting. My only regret was the lack of challenge. On my first try, I didn't understand anything so I slowly died. Then I read the instructions, and went to level 10 without any problem on my second try. I stopped to play intentionally so I could come back here and write this message.
How to make it more challenging without changing it too much ? Well, I found this vampire disturbingly oppressing yet rather unoffensive. You may slow him, proportionally to the cloud meter or not, and he could also deal much more damages.