Full Text Search :SQL Server 2012
You said that you have already installed the feature,
but when you look at the sql server configuration manager do you see it there?



according to the documentation:

IsFulltextInstalled The full-text component is installed with the current instance of SQL Server.

0 = Full-text is not installed.

1 = Full-text is installed.

NULL = Invalid input, or error.

Here you can find a detailed way to install Full Text on SQL Server 2012:

Directions:


Open the Programs and Features control panel.
Select Microsoft SQL Server 2012 and click Change.
When prompted to Add/Repair/Remove, select Add.
Advance through the wizard until the Feature Selection screen. Then select Full-Text Search.


 





On the Installation Type screen, select the appropriate SQL Server instance.
Advance through the rest of the wizard.


Source (with screenshots): http://www.techrepublic.com/blog/networking/adding-sql-full-text-search-to-an-existing-sql-server/5546

This link is also a GREAT article, but a bit more comprehensive:

Step-by-Step: Enabling Semantic Search on SQL Server 2012


  Semantic Search is a powerful new addition to SQL Server 2012.
  Semantic Search builds upon the full-text index feature and adds the
  ability for SQL Server to determine key words in documents. Uses can
  include analysis of text to determine similarity between two
  documents, extract key words from documents, or find documents that
  contain key words.
  
  Step-by-step, enabling Semantic Search on a column in SQL Server 2012
  involves:


1.Install the Full-Text and Semantic Extractions for Search feature

2.Install the Microsoft Office 2010 Filter Packs and Service Pack 1

3.Install, attach and register the semantic language database

4.Create a full-text catalog

5.Create a full-text index with the Statistical_Semantics option enabled

Please visit this link for more details on the above instructions. There are pictures and more detailed info you can find there.

If you have this error message:


  Full-Text Search is not installed, or a full-text component cannot be
  loaded


when you run these procedures below:

EXEC sp_fulltext_service @action='load_os_resources', @value=1; 
EXEC sp_fulltext_service 'update_languages'; 
EXEC sp_fulltext_service 'restart_all_fdhosts'; 


Then:

Check up what you find in the files below:

File    Path
Summary.txt   %programfiles%\Microsoft SQL Server\nnn\Setup Bootstrap\Log

Summary__Date.txt  %programfiles%\Microsoft SQL Server\nnn\Setup Bootstrap\Log\YYYYMMDD_hhmmss

Detail.txt  %programfiles%\Microsoft SQL Server\nnn\Setup 
Bootstrap\Log\YYYYMMDD_hhmmss

Datastore   %programfiles%\Microsoft SQL Server\nnn\Setup Bootstrap\Log\YYYYMMDD_hhmmss\Datastore

MSI Log Files   %programfiles%\Microsoft SQL Server\nnn\Setup 
Bootstrap\Log\YYYYMMDD_hhmmss\.log

ConfigurationFile.ini   %programfiles%\Microsoft SQL Server\nnn\Setup Bootstrap\Log\YYYYMMDD_hhmmss

SystemConfigurationCheck_Report.htm %programfiles%\Microsoft SQL Server\nnn\Setup Bootstrap\Log\YYYYMMDD_hhmmss

For unattended installations    %temp%\sqlsetup*.log

and also check sql server error log

Based on the information you get from the logs, you might need to deal with it accordingly, hopefully avoiding having to reinstall anything.

If you see this error message:


  The specified schema name "sys" either does not exist or you do not
  have permission to use it.


Check if you have enough permissions to run these procedures.

In regards to permissions the minimum requirement is:


  On SQL Server, requires VIEW SERVER STATE permission. On SQL Database
  Premium Tiers, requires the VIEW DATABASE STATE permission in the
  database. On SQL Database Standard and Basic Tiers, requires the
  Server admin or an Azure Active Directory admin account.