Hm. According to the internet, Google IME is just “-” which is the same as Windows’ Japanese IME. My only thought might be related to it being a Euro keyboard. Maybe try the Microsoft IME? That’s what I use, and once you get the STUPID keyboard shortcuts figured out it works pretty well. ALT+SHIFT to switch keyboards, ALT+CAPS to change from romaji to hiragana, again to get to katakana, but then CTRL+CAPS to get back to hiragana. Otherwise everything should be the same as Google. Space to scroll through words, enter to input.
I haz a blog http://maninjapanchannel.wordpress.com/
https://www.youtube.com/watch?v=qLQzB-1u-dg