Im gonna play devils advocate and say you did an OK job...(If you indeed sounded as confident as you claimed too).... The real problem wasn't your opener but the fact that you didn't build any rapport during your meeting with her therefore she's likely to "flake"....
If all you did was send her an email that said "Hello" she could have just thought it was SPAM since she doesn't know who you are.... Try this for the Hell of it: Create a new email account with a name like "
HOT_Guy_You_Met_At_Work@yahoo.com" or something else catchy....Send another email saying something short and witty and link it to your FaceBook.... See what happens cause you got nothing to lose...