ImageMagick install fails w/ zlib error

[dorfman@…]

I'm new to MacPorts, but I don't think I'm doing anything unusual. I have a fresh install of MacPorts 1.6, for the sole purpose (at this point) of installing ImageMagick. I am getting a failure indicating that I do not have zlib, although it does appear in 'port installed'.

I have literally done nothing but install MacPorts and then issue the following command:

   sudo port install tiff -macosx imagemagick +q8 +gs +wmf

(which I got from here: ​http://rmagick.rubyforge.org/install-osx.html)

Here is the error message I'm getting:

Error: Target org.macports.configure returned: configure failure: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_tiff/work/tiff-3.8.2" && ./configure --prefix=/opt/local --mandir=/opt/local/share/man --with-docdir=/opt/local/share/doc/tiff-3.8.2 --with-jpeg-include-dir=/opt/local/include --with-jpeg-lib-dir=/opt/local/lib --with-zlib-include-dir=/opt/local/include --with-zlib-lib-dir=/opt/local/lib " returned error 1
Command output: checking for int... yes
checking size of int... 4
checking for long... yes
checking size of long... 4
checking whether time.h and sys/time.h may both be included... yes
checking whether struct tm is in sys/time.h or time.h... time.h
checking for int8... no
checking for int16... no
checking for int32... no
checking for floor... yes
checking for isascii... yes
checking for memmove... yes
checking for memset... yes
checking for mmap... yes
checking for pow... yes
checking for sqrt... yes
checking for strchr... yes
checking for strrchr... yes
checking for strstr... yes
checking for strtol... yes
checking for getopt... yes
checking for strcasecmp... yes
checking for strtoul... yes
checking for lfind... yes
checking native cpu bit order... lsb2msb
checking for special C compiler options needed for large files... no
checking for _FILE_OFFSET_BITS value needed for large files... no
checking for _LARGE_FILES value needed for large files... no
checking for inflateEnd in -lz... no
configure: error: Zlib library not found at /opt/local/lib

Error: Status 1 encountered during processing.