Search facility doesn't find all entries

I'm puzzled why the Search App on my 8830 provides inconsistent results when searching the Calendar. Say I have a Sample Board meeting entered as recurring on the third Wednesday of every month in 2011. If I search the calender for the Text: Sample, I only receive 8 returns instead of 12 even though I've checked and there are 12 entries. On some, however, I had to go in and change a location. In viewing the entries returned using Search, the blue "recurring" symbol shows on the right side of the line. The 8 which show up have a red slash through the "recurring" symbol. The 4 entries which I made no changes to do not show up from the search. Any ideas?