I had this problem last night when I placed my second order. I ended up not putting in the correct exp. date for my cc. I noticed it after the third time trying to place the order. I fixed it and it went through.
Did you make sure you typed in the number and all the info for your cc correctly? I would try again. Otherwise, try and call and place a phone order.
The second thing that happened is that cc companies are putting in these fancy algorithims to flag possible fraud transactions. For example, if you typically only do 5 transactions a day and all of a sudden there are 10 transactions the cc company will flag the card and not authorize the transaction unless you call in. This happened to me too because I usually only do about 7 transactions a day. So one day I placed an 8th transaction (GAP kids sale) for a large amount and they didn't authorize it. I called in and they authorized the transaction and everything was cool. They are just doing all this to protect you against someone stealing your cc; and to protect themselves too. If this is the case I bet if you placed the order today you will be fine.