When asking a girl on a date--either via text, call, or in person--always pose it as a statement, not a question.
*"I'm gonna go see a show at the jazz club Wednesday night at 7. You should^1 join me."
Simple, straightforward, unassuming. It lays out the time and place in one sentence. You aren’t asking her if she’s free or where she wants to go or what she wants to do. Posing it as a question just gives her an opportunity to decline. Remove that opportunity. YOU are going to do something awesome that night regardless if she’s available or not, but it sure would be cool if she joined. Girls hate having to plan stuff, especially dates. It's too stressful and onerous for them. Take the initiative; be the man. She's less likely to decline or flake if you have things already planned out.
Keep your life interesting and she'll follow.
^1Side note: Using the word "should" in this case is so simple yet so powerful. It makes her feel like she would be missing out on a golden opportunity to do something fun with you. It's almost like you are incepting the thought into her mind. You "should" use this word it as often as you can.