I keep bumping into a problem when trying to update my sqlite3.

Here is what the terminal displays:

christopher-berrys-macbook-pro:~ rubyadmin$ gem update sqlite3
Updating installed gems
Updating sqlite3-ruby
WARNING: Installing to ~/.gem since /Library/Ruby/Gems/1.8 and
/usr/bin aren't both writable.
WARNING: You don't have /Users/rubyadmin/.gem/ruby/1.8/bin in your PATH,
gem executables will not run.
Building native extensions. This could take a while...
ERROR: Error installing sqlite3-ruby:
ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for fdatasync() in -lrt... no
checking for sqlite3.h... yes
checking for sqlite3_open() in -lsqlite3... no

make: *** No rule to make target `ruby.h', needed by `sqlite3_api_wrap.o'. Stop.

Gem files will remain installed in /Users/rubyadmin/.gem/ruby/1.8/gems/sqlite3-ruby-1.2.4 for inspection.
Results logged to /Users/rubyadmin/.gem/ruby/1.8/gems/sqlite3-ruby-1.2.4/ext/sqlite3_api/gem_make.out
Nothing to update
christopher-berrys-macbook-pro:~ rubyadmin$

Any help would be great.