Isolating a girl can be tricky and complicated sometimes. Sometimes going with you may be a lot of compliance. She needs to stand up, move out of the table, seek for permission of the group, and go with you. It will be much easier for you to ask her to do it step by step giving her reasons for every move.
Ex.: you look at your hand and say, "Hmm, interesting. Can I see you hand for a second?"
Take her hand, then say, "Could you please stand up?
Come closer for a moment I'm gonna show you something!"
When she gets out of the table, you may play a Kino game with her (something like back writing game, hand slapping game, push me game etc.) If she asks for reasons, give her reasons (last night a girl at a party taught me this game and I couldn't win once, you look like her, so I want to win, or any other illogical crap).
Now that she is standing and practically interacting only with you, you can ask her to move further, you can ask her for help (to choose a drink, reply to another girls text, etc.), or say you need a drink and she reminded you of something that you need to tell right now, take her hand and lead.
Do not project any importance of your move!
Ninja move: you start telling her an engaging story and in the middle you drop, "I want another drink" or "Its too loud here, lets move over there", and continue your story, grab her hand and move. She has no time for thinking, she is interested in the story, it is rude to interrupt you in the middle, but most of all - her brain is occupied by your story, her body just follows you. You are the leader - alpha male - Boom! she is yours before she knows it.
Optional (this is what I do): When you have isolated her, spin her and go for a kiss; independently of the result continue telling your story, as if nothing happened