php-4.3.2 errors upgrading from php-4.3.1

Dear List, I'm using the following configure line: (which configures & compiles fine on php-4.3.1) './configure' '--with-apxs=/usr/local/httpd/bin/apxs' '--with-config-file-path=/usr/local/httpd/conf' '--with-xmlrpc' '--with-xml' '--with-freetype-dir=/home/system/src/freetype-2.0.9' '--with-gd=/usr' '--with-gdbm=/usr' '--with-jpeg' '--with-jpeg-dir=/home/system/src/jpeg-6b' '--with-png' '--with-png-dir=/home/system/src/libpng-1.2.1' '--with-zlib' '--with-zlib-dir=/home/system/src/zlib-1.1.4' '--with-mysql' '--enable-gd-native-ttf' '--enable-ftp' '--enable-sockets' '--enable-track-vars' '--enable-trans-sid' '--enable-exif' when I configure php-4.3.2 with this line it won't configure, giving the following error: (with some other stuff for context) checking for FreeType 2... /home/system/src/freetype-2.0.9 checking for T1lib support... no checking whether to enable truetype string function in GD... yes checking whether to enable JIS-mapped Japanese font support in GD... no checking for jpeg_read_header in -ljpeg... yes configure: error: png.h not found. I looked in the configure file but sadly this same error is given in about six places so its not easy to figure out where things are gonig off the tracks. Anyhow anyone have any insight as to whats different in the configure files between 4.3.1 and 4.3.2 that might be causing this problem? Thanks so much, Nate