Redmine

My OS is Redhat 5.5. I'm trying to install Redmine 2.1.2

When I execute the following command: # gem install --local rake actionmailer actionpack activerecord activeresource fastthread rack rails RedCloth passenger rmagick jquery-rails coderay fastercsv net-ldap rack-openid activerecord-mysql2-adapter factory_girl_rails simplecov-html simplecov-rcov libxml-ruby

I encounter the following errors :
• ERROR: Error installing activerecord: / ERROR: Failed to build gem native extension.
• ERROR: Error installing activerecord-mysql2-adapter: / ERROR: Failed to build gem native extension.

When I'm looking for the compilation log files, I have a lot of error like these :
conftest.c:5: error: ‘mysql_query’ undeclared (first use in this function)
conftest.c:5: error: (Each undeclared identifier is reported only once
conftest.c:5: error: for each function it appears in.)
checked program was:

Could you help me please ?