Here is one person who failed using Strip NC
http://boards.cannabis.com/showthread.php?t=86632

Here is someone who passed
http://boards.cannabis.com/showthrea...ighlight=strip

Another failure.
http://boards.cannabis.com/showthrea...ighlight=strip
Strip NC is anything but a 100% success rate. It may also have something to do with people drinking a lot with it.

You should switch to a sports drink instead of water BTW. You should be measuring your fluid intake to avoid a dilute sample. You should have started with around 64 ounces and every time you void, replace what you void.