DOM XML install problem

[amcgrath]

All:

I am trying to recompile php with dom support. I've done the following:

1. Installed libxml2 (libxml2-2.4.9.tar.gz)
2. Recompiled php with --with-dom=/usr/lib

I continually get :
checking for DOM support... yes
checking for DOM in default path... not found
configure: error: Please reinstall the libxml >= 2.2.7 distribution

During ./configure. AM I missing something obvious here? any help is appreciated....