SQL Server 2012: why does full-text search not index .pdf, .cs? -

i have installed sql server 2012, executed

select document_type  sys.fulltext_document_types 

the result 50 extensions, ok.

then downloaded filerpack sp2 microsoft site, installed it, executed

exec sp_fulltext_service 'load_os_resources', 1 exec sp_fulltext_service 'update_languages'  

restarted sql server , executed:

select document_type  sys.fulltext_document_types 

the result 151 extensions including .pdf, .cs , on.

then:

create table documentrepository (     id int not null primary key identity,     filename nvarchar(250),     filesize int,     fileextension nvarchar(10),     attachment varbinary(max) ); go  grant insert,update,select,delete on documentrepository public; go  create fulltext catalog ftscatalog default; go  create fulltext index on dbo.documentrepository (filename, attachment type column fileextension) key index pk__document__3213e83fefb4f2b9 on ftscatalog change_tracking auto; go 

and added files: .pdf, .txt, .cs, .docx

• microsoft project silk.pdf 7963 .pdf
• kdd-camera-ready-final.pdf 354 .pdf
• pro_wcf_4_2nd_edition.pdf 22193 .pdf
• dbw.txt 3 .txt
• mydoc.docx 11 .docx
• rollingfileappender.cs 50 .cs

and executed:

select *  documentrepository  contains(*, n'firefox')   ------ 0, (word inside pdf field)  select *  documentrepository  contains(*, n'appender')  ----- 0, (word inside .cs)  select *  documentrepository  contains(*, n'database')  -------- dbw.txt 3   .txt mydoc.docx  11  .docx 

why fts not search in .pdf, .cs files?