Smack Pack not swelling

I am making a yeast starter using two Wyeast 2278 smack packs. One swelled and one stayed completely flat. So, to make sure the yeast was still good I made two smaller starters. After a couple of hours the one that swelled normally has activity and the other doesn't. Should I buy another smack pack tomorrow before I brew and dump it into my wort? I know it has only been a couple of hours. Should I give it until morning? LHBS said it should still be okay. Date on the good smack pack was Aprit 2012 vs. December 2011 on the flat one. Frustrating! Thanks for your help!

Give it time. The flat one probably has a lot fewer viable yeast. The ones there will munch on that starter and be ready to go tomorrow.

Make sure you blew the bag inside the smack pack. I've hit it freakin hard, had some swelling only to open the yeast to find the nutrient pack full.

After I piched them in their respective bottles with the DME, I ripped the bags open and both nutrient bags were ruptured and empty. Maybe in the morning I will see something positive........I hope. I am going to buy the rest of my ingredients in the morning, so I may need to buy another smack pack.