I've followed the faq and still getting too many clients errr

Help!

I've recompiled pg. Here is what I did to
correct 'too many clients' error

I just change the following line in src/configure
#define DEF_MAXBACKENDS 32
to
#define DEF_MAXBACKENDS 100

Did I do that right? After ./configure I check
src/include/config.h and see that previous number 32
has been changed to 100.

Before I did the recompile I attempt to restart
postmaster with
-N 100 -B 200
options. I get the following error
--------------
IpcMemoryCreate: shmget failed (Invalid argument) key=5432001, size=1929216, permission=600
This type of error is usually caused by an improper
shared memory or System V IPC semaphore configuration.
For more information, see the FAQ and platform-specific
FAQ's in the source directory pgsql/doc or on our
web site at http://www.postgresql.org.
FATAL 1: ShmemCreate: cannot create region
------------
After recompiling I still use the same
options and get the same error. So
I assume that after recompilation I don't
need to set the options manually and
maximum will be automatically set to 100 etc..

That is not the case... I am still gettiing
'too many clients error'

As an aside after the recompilation I get a new error

-------------------
pq_flush: send() failed: Broken pipe
pq_flush: send() failed: Broken pipe
pq_flush: send() failed: Broken pipe
---------------

like above before getting too many clients errors
again.

I really don't think I've reached 100 backends
because top says that I have 90 processes altogether
of which some are other processes..

linux 2.4.1 red hat 6.2

I'm in complete dodo now.. I've never expected
this many hits and I really don't know what I can
do to fix this continuous problem.

Thanks much in advance for your help

kz

I am still getting too many clients error.