I recently made an IPA. I put an ounce of Cascade pellets in the secondary (for a 23-litre [6-U.S.-gallon] batch), but there is hardly any hops aroma in the finished product. By the end of the two weeks, the hops had all sunk to the bottom, so I know they were exposed to the beer and not just floating. Is an ounce not enough? Is there some other way this could have failed? I trust my LHBS and would assume that they sold me fresh, properly-stored ingredients.
I was using Danstar Nottingham yeast, which is highly-flocculating. Could that have pulled the dry hops out of the wort and deposited it in the trub during the secondary phase?