Why does this happen?

This is one of my pet peeves!  Why does this happen?  The flowers don't open, they just nod their beautiful heads and dry up!  The water has the special added ingredient, there are no leaves in the water and the water is fresh.  I've had this happen to flowers delivered from the florist as well.  Beautiful bouquets that are very expensive - never open!  I find it happens alot and that is why I don't really care to buy flowers from the florist! (Sorry Stacy!)  I always tell my husband not to order me flowers for any special occasion because this always happens (especially to roses).  It bums me out!