error building mhash extension for php

 i have to install mcrypt for php and i did it successfully on our dev box. but when trying to replicate on qa server, i've run into a snag and cannot get past it.

 i got the .gz files for mycrypt, libmcrypt, and mhash. i built them and did make install on them successfully. now, i have to do the following forthe php extension mhash and mcrypt which is to go to php_src_dir/ext/mhash and do the usual configure,e tc...

i was able to build mcrypt (after having to set the LD_LIBRARY_PATH variable) but when i try to ./configure it in the php_src_dir/ext/mhash  i get this error :

 checking for mhash support... yes, shared
configure: error: Please reinstall libmhash - I cannot find mhash.h




i even tried :
CFLAGS="-I/usr/local/mhash/include -L/usr/local/mhash/lib" ./configure --with-prefix=/usr/local/mhash && make

nothing seems to help me get past this error. any help would be appreciated.
it's php 5.2.9
mcrypt-2.6.7.tar.gz
libmcrypt-2.5.8.tar.gz
mhash-0.9.9.tar.gz