config.m4 possibly undefined macro

Hi, I'd like to call my extension "utrac", but when I run phpize, it returns the following error : error: possibly undefined macro: AC_SHARED_LIBADD But if I name my extension "ut" instead of "utrac", I don't get this error. Do you know why there is such an error with some names ? Thanks in advance. Here is my config.m4 for this extension: PHP_ARG_WITH(utrac, for utrac support, [ --with-utrac Include utrac support]) if test "$PHP_UTRAC" != "no"; then SEARCH_PATH="/usr/local /usr" SEARCH_FOR="/include/utrac.h" if test -r $PHP_UTRAC/; then UTRAC_DIR=$PHP_UTRAC else AC_MSG_CHECKING([for utrac files in default path]) for i in $SEARCH_PATH ; do if test -r $i/$SEARCH_FOR; then UTRAC_DIR=$i AC_MSG_RESULT(found in $i) fi done fi if test -z "$UTRAC_DIR"; then AC_MSG_RESULT([not found]) AC_MSG_ERROR([Please reinstall the utrac distribution]) fi PHP_ADD_INCLUDE($UTRAC_DIR/include) LIBNAME=utrac LIBSYMBOL=ut_init PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL, [ PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $UTRAC_DIR/lib, UTRAC_SHARED_LIBADD) AC_DEFINE(HAVE_UTRACLIB,1,[ ]) ],[ AC_MSG_ERROR([wrong utrac lib version or lib not found]) ],[ -L$UTRAC_DIR/lib -lm ]) PHP_SUBST(UTRAC_SHARED_LIBADD) PHP_NEW_EXTENSION(utrac, utrac.c, $ext_shared) fi For reference, someone else also asked this question before, but for an extension named "vault" : http://stackoverflow.com/questions/5252732/php-extension-config-m4-possibly-undefined-macro-lt-shared-libadd PS: if this is not the right place to ask questions about php extension development, please direct me to a more suited place, since I might have other questions to ask in the near future... -- Bertrand Mansion Mamasam