[xsl] String-length of substring-before is giving me wrong number

["J. Zhang" <j.zhang@xxxxxx>]

Hi all,

I have got a string:

"Yoshimi Battles the Hip-Hop Robots"

The $keyword = hip

I count the substring before the $keyword like this:

string-length(substring-before($string, $keyword))

When I count the length before the keyword, it returning to me 0, which 
is wrong.

I do not understand why it is returning me 0...

Thanks,
  jz