Make rule not taken although it matches

[Sebastian Schuberth]

Hi,

in my makefile I have two simple rules:

prefix_%.s: prefix_%.c
        # Do something

prefix_%.o: prefix_%.s
        # Do something

The file prefix_test.c exists. When I type "make prefix_test.o", instead 
of my rule some default rule (which is not present in the file) 
launching "cc" is run. However, running "make prefix_test.s" works, and 
running "make prefix_test.o" afterwards (so prefix_test.s exists) works 
then, too. Why is that? Why can't I create both "prefix_test.s" and 
"prefix_test.o" in a single step by launching "make prefix_test.o"?

Thanks for any insights.

--
Sebastian Schuberth