You cannot shrink past the marked active portion of the log.

If the portion of the log was released and another earlier portion of the log marked as active then you could shrink the file to the new active portion of the log.

Managing Transaction Logs - http://www.sqlservercentral.com/articles/Administration/64582/

Why is my transaction log full - http://www.sqlservercentral.com/articles/Transaction+Logs/72488/

Now have you done your investigations into what caused the log to grow? Is it general day to day usage? Missing transaction log management? etc etc.

You detailed you shrunk some files, what files did you actually shrink? Data files, log files? Have you rechecked for the after effects of shrinking files like fragmentation etc and took the nessesary steps to remove the after effects?