It is not realistic to expect every mentor and mentee to instantaneously bond and become very close. If you do not feel comfortable discussing some issues with your mentor, try to focus on what you can learn from that person and look for other informal mentors for other needs.
Unrealistic Expectations for Mentors or Mentees
Occasionally, mentors and mentees expect too much from one another. Realize that the other person is busy or life may have gotten in the way. Try to be understanding and appreciative of what you get from the relationship. Mentees, you should not expect your mentor to "make your career" or give you all the answers. Mentors are one source of advice and encouragement; no one should rely on one person for everything.
Lack of Commitment
If your mentor or mentee seems unresponsive for a long period of time, send another e-mail assuming he/she is just busy. If you still don't get a response, then write or call again, asking if something is wrong.