'You're in too deep!"
that's what she said, hardy fuckin har har!
Anyway, yeah...as a long time needle user, it's rare that I just push it in all the way and I'm in the vein....It's all about maintaining the depth while you push the plunger down! Putting it in a little deeper....pulling it out a little...It sounds very sexual, but it's kind of what you have to do to master the needle!
to the OPs credit....sometimes it doesn't seem to matter WHAT you do! You know you're in the vein and yet, you still get NO blood! Not sure if it's your technique, or if it's a case of it just not happening for some unknown reason....but I'd be pretty pissed if I was a master at finding other peoples veins, and then I came here asking for advice, and THEN everybody on BL just told me, "You have shitty technique!".....lol
You may have good technique! you may just be dealing with somebody with shitty veins OP! It happens.....