Hello everyone!

I've been reading around this forum, lots of great information! I was hoping someone can let me in on the secret for bass flutes. I just got a brand new bass flute for the flute choir I'm gonna start here in a couple months (the ubiquitous Jupiter 523), and I can get a good tone in the lower register from F# on up to D in the middle register, but around middle register D/Eb/E/and F to an extent, I have the hardest time getting these notes out. Lower register I know I just need to work with, but I wouldn't think that I should have any problems in the middle register. But they are so weak and anemic (when they even come out at all), its driving me crazy. Are these common notes to have issues with, or is it just me?

Thank you!
Chris