toadyus said:
sorry not hissing but a fizzing sound...when I push on the bag it doesn't budge now...so I doubt there is a hole in the bag
Then that would be the faint sound of your yeast burning through the nutrient in the little inner cell you popped. You're fine. If in serious doubt, submerge the package in water and look for bubbles. Even if you have a pinhole leak you're probably still fine if you pitch the yeast in a reasonable amount of time.
Some things to note:
A) You can pitch a Wyeast Activator (125ml) pack without smacking it. The yeast is in the main pouch. The inner packet is yeast nutrient that wakes the little buggers up and gets them raring to go -- good, but not strictly necessary.
B) Before smacking, feel for the inner cell. It feels about the size of a business card and is slightly thicker and more resistant than the outer foil pack. You can feel it slide around inside. Move it to one corner just to keep track of it and pop it with a firm blow from the heel of your hand. You'll notice its absence afterward.
C) Just feeling around for the nutrient pack will probably do it, but you should also agitate and squeeze the whole pack to distribute the nutrient so the yeasties can get at it.
D) It generally takes an hour or more to see definite swelling. You'll definitely notice it after two. After four hours you'll worry that the whole thing is going to blow, spewing yeast slurry all over your kitchen. This is at US room temperatures of approximately 70F.
E) When you are ready to pitch, dunk the packet in your sanitizing solution (you do have a bucket of it for all your post-boil sanitation needs, don't you?) just to be safe. Cut or tear one corner. That gives you a smaller, more controllable opening to pour from and the spent nutrient packet doesn't end up in your wort. Yes, this happened. Twice.
Hope this helps,
Chad