Robots.txt need suggestions!!!

Is there anything wrong with this robot file, I am little confused here because the indexation is little low for this website and the site itself has more than 19,000 pages but only 5000 are currenlty indexed.

User-agent: *

Disallow:

User-agent: ia_archiver-web.archive.org

Disallow: /

User-agent: ia_archiver

Disallow: /

User-agent: TurnitinBot/2.1

Disallow: /

User-agent: TurnitinBot

Disallow: /

User-agent: SurveyBot

Disallow: /

User-agent: EmailWolf

Disallow: /

User-agent: EmailSiphon

Disallow: /

User-agent: EmailCollector

Disallow: /

User-agent: AboutUsBot

Disallow: /

User-agent: robtexbot

Disallow: /

User-agent: spybot

Disallow: /

​

User-agent: spyfu

Disallow: /