How to use TLS 1.2 in Ruby Http client

I'm trying to access third party api using TLS 1.2, but getting SSL error event with valid certificates

Ruby Version:

 ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-linux]

Rails Version:

Rails 4.2.5

CODE:

    ua = Net::HTTP.new(SERVER, 443)    ua.instance_eval {      @ssl_context = OpenSSL::SSL::SSLContext.new      options = OpenSSL::SSL::OP_NO_SSLv2 | OpenSSL::SSL::OP_NO_SSLv3      if OpenSSL::SSL.const_defined?('OP_NO_COMPRESSION')        options |= OpenSSL::SSL::OP_NO_COMPRESSION      end      @ssl_context.set_params({options: options})    }   # ua.instance_eval { @ssl_context = OpenSSL::SSL::SSLContext.new(:TLSv1_2) }    ua.use_ssl = true    # Checks presence of CA certificate    if File.directory?(RootCA)      ua.ca_path = RootCA      ua.verify_mode = OpenSSL::SSL::VERIFY_PEER      ua.verify_depth = 3    else      puts "Invalid CA certificates directory. Exiting..."      exit    end

ERROR:

OpenSSL::SSL::SSLError: SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:933:in `connect_nonblock'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:933:in `connect'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:863:in `do_start'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:852:in `start'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:1398:in `request'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:1421:in `send_entity'    from /home/cp/.rbenv/versions/2.3.0/lib/ruby/2.3.0/net/http.rb:1209:in `post'