compatibility problems: win7 prof 64 bits

[ice_zero_cool]

Hi there, it's me again.

I bought a new computer few days ago - or rather new parts for my old computer, including a 64-bits copy of "Windows 7 Professional".
I know, that the windows version of Regnum Online works with both, 32bits and 64bits - normally.
Now, when I try to install regnum to my computer, I get the following error message (I'll translate it myself, since most of you would not understand any German... probably. So in reality, the phrasing could be something different):
"The release of this data/program is not compatible with the running windows version. Open up the system information of your computer to check if a x86(32-bits) or a x64(64bits) version of the program is needed and afterwards address the publisher of the software".

Again, I appreciate everything that I can try.
If you need to know the hardware of my PC, feel free to ask.

ice