Can probiotic yogurt cause diarrhea?

I understood that probiotic yogurt would remove diarrhea, but after eating some, the next day I had diarrhea. This has happened three times.

Or is there something to the "Activia 14 Day Challenge" where I have to keep eating it for 2 weeks before seeing an improvement?

(I can drink a medium glass of milk without getting diarrhea, so I figure 5 tablespoons of yogurt wouldn't trigger lactose intolerance.)