If you're not getting a response from a txt you sent to a HB you met on a night out then you may want to try sending one a few days later saying
"Hey, just wondered if you still fancied going out sometime this week. It's just I've been asked out by this girl and don't tend to organise more than one date at a time as things always get v complicated. I'd really like to continue [enter details of some fun convo you had here]"
This not only demonstrates social value but also gives a loose time constraint.
I've only tried this when this has actually been true but it's worked well...