Having problems with updating the version of bison on mac

[Niklas]

Hello there,
I am a student from germany and I have quite an issue which I can't deal 
with yet.

I need bison 3.0 and I downloaded the tar.gz-File from the homepage and 
run "./configure; make; make install" just as the 
INSTALL-File-Instructions are given. However, if I type "bison 
--version" into the terminal it shows this:

"bison (GNU Bison) 2.3
Written by Robert Corbett and Richard Stallman.

Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE"

I tested this with some exercise files and it says:

"bison -v -d -o calc++-parser.cc calc++-parser.yy
calc++-parser.yy:16.10-16: require bison 3.0.2, but have 2.3
make: *** [calc++-parser.hh] Error 63"

I seriously don't get why the version is 2.3 while I clearly have 3.0 (I 
also checked via "make check" and "make installcheck" that everything is 
correct) and I can't find any hints (checked with google of course).

Please help me.

Greetings
Niklas Breuer