Cmake Project, new class does not compile

[Ulrich Mierendorff]

Hi,
I posted the same in the forums, but it looks like if only a few people 
are looking into it. So I repost my question to this mailing list.

I chose a CMake based Project -> shared library. It creates some files, 
creates a test-class and a test app. Compiling works ok. If I create a 
new class for that project using the class wizard and recompile, this 
class did not get compiled. If I try to click "compile file" the message 
is (the class is called "cache"):

cd '/home/bla/blubproject/src' && make -k -j1 'cache.o'
make: *** Keine Regel, um »cache.o« zu erstellen.
*** Exited with status: 2 ***

I would translate the second line as:
"make: *** No rules to create »cache.o«"

Am I doing anything wrong? How to I set up a new class to be compiled? I 
thought everything is automatic?
I looked into the documentation but it says nothing about cmake projects...

Thanks in advance.

Ulrich