configure in libhtdigphp looking for libhtdig_api.h

Hello htdig-devs,

In configure of libhtdigphp  I am having this error:

<--screen dump begin-->

[root@server libhtdigphp-2]# ./configure
loading cache ./config.cache
checking for gcc... (cached) gcc
checking whether the C compiler (gcc  ) works... yes
checking whether the C compiler (gcc  ) is a cross-compiler... no
checking whether we are using GNU C... (cached) yes
checking whether gcc accepts -g... (cached) yes
checking whether gcc and cc understand -c and -o together... (cached) yes
checking for PHP prefix... /usr
checking for PHP includes... -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/Zend -I/usr/include/php/TSRM
checking for PHP extension directory... /usr/lib/php4
checking for HtDig support... yes, shared
checking for HtDig in default path... not found
configure: error: Please reinstall the HtDig distribution
[root@server libhtdigphp-2]

<--screen dump end-->

My HtDig distribution (htdig-3.2b5-libhtdig) is installed freshly and works smoothly (htdig indexing and htsearch giving results).

I already 'make' libhtdig successfully with minor warnings (deprecated headers).

now, configure in libhtdigphp-2 make this check:

<--extracted code begin-->
...
if test "$PHP_HTDIG" != "no"; then

  if test -r $PHP_HTDIG/include/libhtdig_api.h; then
    HTDIG_DIR=$PHP_HTDIG
  else
    echo $ac_n "checking for HtDig in default path""... $ac_c" 1>&6
echo "configure:1067: checking for HtDig in default path" >&5
    for i in /usr/local /usr; do
      if test -r $i/include/libhtdig_api.h; then
        HTDIG_DIR=$i
        echo "$ac_t""found in $i" 1>&6
      fi
    done
  fi

  if test -z "$HTDIG_DIR"; then
    echo "$ac_t""not found" 1>&6
    { echo "configure: error: Please reinstall the HtDig distribution" 1>&2; exit 1; }
  fi
...
<--extracted code end-->

It's obvious that I have to have libhtdig_api.h in some /usr/local/include/ or /usr/inlcude directory 
 Why is not there? Do I have to move it there manually ? What else do I have to copy from libhtdig dir to include or lib ?

right now I have libhtdig_api.h only here:

[root@server libhtdigphp-2]# locate libhtdig_api.h
/src/htdig-3.2b5-libhtdig/libhtdig/libhtdig_api.h

Readme doesn't say anything about this, and I want to have this libraries in the right place before continue.
I would really appreciate your help.

Roger Moreno