Ahhh... the Holy Grail of texting a girl... getting them to text you first.
i have had this problems many times because i like having a lot of long distance relationships and texting is an important part of that.
1st a couple of things i want to know if you are doing.
Are you controlling the tempo? If she takes 1 hour to reply your text, are you texting back right away after she replies or wait a Minimum of 30 min before replying?
Do you ask a lot of questions in your texts or make a lot of statements? Nothing says im on your nuts like texting questions after questions.
Are you always the last text sender? If she text something that doesn't really need a reply, do you HAVE to reply?
Example: Her: " Oh, no problem, anytime."
you: (any one of the following) cool! your so nice! Thats awesome of you!
Do you freeze her out? This one is hard to do and a lot of times, you have to be prepare to lose her. I've frozen girls out and lost them and i've frozen girls out to have them initiate texting me again after 2 month...
You have to realize tho, MOST HOT girls HB7's and above, usually don't initiate any texts. Thats just how it is. You really don't get a lot of starter texts from a girl unless 1) They are IN LOVE with you or 2) You have built a lot of Comfort
More info on your situation would help too, and as always, this is just my opinion