brackets change but need only from 'where' to end.

Hello, I have problem with my code.
Here is my code: http://paste.php.lv/ddbd56642652602e4760a3c187b1e944?lang=csharp
The problem is whan I enter - select len(aaa) from bbb where a=1 or a=2 or a=3 and b=2 or b=3 and c=2 or c=3
My code colors 'select, len, where, or, and'.
Whan press button it makes brackets from where to end and
makes likes this - select len(aaa) from bbb where ((a=1 or a=2 or a=3) and ((b=2 or b=3) and ((c=2 or c=3))))
But whan I press again button it's replace all '(' and ')' with ' '.
And ends again brackets.
len(aaa) is replaced to lenaaa and it's not correct.
Maybe can someone help me out, how to solve this problem ?