This is just IMO, but it's because you're not expressing any dependency toward them. I think they want to lure you to feel it and then to express it, and then they will shut you down to frustrate you and force you to analyze how dependent you feel.

When I started I was feeling very needy for my therapist, but I also was unable to contact him out of session because it felt too ridiculous to me... I knew he would immediately see through whatever text or email I sent and see it as me being needy, and that was too much for me. He found excuses to contact me, and subtly encouraged me in other ways, until I felt comfortable enough to engage in some minimal out of session contact. Then just as quick as it started he shuts it down, forgets to reply to my email, doesn't return my text, effectively leaving me frustrated and thinking about it. It's taken me a while but I am now confident this is a very common therapeutic technique, possibly it is the crux of therapy as I know it... they pull you in and then when you come in reluctant and frightened they push you out, tell you youre childish and force you to think about what just happened.