Helen, have you checked the YES TRAILING and NO TRAILING sentence in your GSG? As you can see from some of my previous posts, reading your GSG I've understood that this property is referring to BLANKS, but it's not!
From the help, or the code, you learn that
"IB_NOTRAILING = 'NOTRAILING' : Flag to use STARTING on literal strings"
so, as my tests shown, this property affects search switching from exact match to near match, regardless blanks
thanks
Marco Menardi