php 安装错误，每次都是这个问题

libtool libtool-ltdl 都已经安装还是出现问题

chmod 755 /usr/local/apache2//modules/libphp5.so
[activating module `php5' in /etc/httpd//httpd.conf]
Installing PHP CLI binary:        /usr/local/php//bin/
Installing PHP CLI man page:      /usr/local/php//man/man1/
Installing build environment:     /usr/local/php//lib/php/build/
Installing header files:          /usr/local/php//include/php/
Installing helper programs:       /usr/local/php//bin/
  program: phpize
  program: php-config
Installing man pages:             /usr/local/php//man/man1/
  page: phpize.1
  page: php-config.1
Installing PEAR environment:      /usr/local/php//lib/php/
/lamp/php-5.2.6/sapi/cli/php: error while loading shared libraries: libltdl.so.3: cannot open shared object file: No such file or directory
make[1]: *** [install-pear-installer] Error 127
make: *** [install-pear] Error 2

# 安装libmcrypt
cd /lamp/libmcrypt-2.5.8
./configure --prefix=/usr/local/libmcrypt/
make
make install
* 需调用gcc-c++编译器，未安装会报错

# 安装libltdl，也在libmcrypt源码目录中，非新软件
cd /lamp/libmcrypt-2.5.8/libltdl
./configure --enable-ltdl-install
make
make install

这两个软件我都安装 了的，没有报错

是不是centos6.0和5.5差别的原因？