安装php后httpd运行不起来

[hero@centos6 ~]$ sudo service httpd start 
Starting httpd: httpd: Syntax error on line 200 of /etc/httpd/conf/httpd.conf: Cannot load /etc/httpd/modules/libphp5.so into server: libpng15.so.15: cannot open shared object file: No such file or directory
                                                          [ FAILED]
[hero@centos6 ~]$ ldd /etc/httpd/modules/libphp5.so 
linux-gate.so.1 =>  (0x00299000)
libcrypt.so.1 => /lib/libcrypt.so.1 (0x005b8000)
librt.so.1 => /lib/librt.so.1 (0x003ef000)
libldap-2.4.so.2 => /home/hero/lib/libldap-2.4.so.2 (0x00bdc000)
liblber-2.4.so.2 => /home/hero/lib/liblber-2.4.so.2 (0x001ff000)
libfreetype.so.6 => /usr/lib/libfreetype.so.6 (0x00864000)
libpng15.so.15 => /home/hero/lib/libpng15.so.15 (0x001c0000)
libjpeg.so.62 => /usr/lib/libjpeg.so.62 (0x00ae5000)
libm.so.6 => /lib/libm.so.6 (0x0039e000)
libdl.so.2 => /lib/libdl.so.2 (0x00994000)
libnsl.so.1 => /lib/libnsl.so.1 (0x00746000)
libc.so.6 => /lib/libc.so.6 (0x003f8000)
libfreebl3.so => /lib/libfreebl3.so (0x009aa000)
libpthread.so.0 => /lib/libpthread.so.0 (0x0020b000)
/lib/ld-linux.so.2 (0x00246000)
libresolv.so.2 => /lib/libresolv.so.2 (0x00fda000)
libz.so.1 => /lib/libz.so.1 (0x001e6000)提示libpng15.so.15找不到，可是通过ldd可以看出libpng15.so.15是存在到啊。