Question: Why doesn't Orthodox Judaism accept Conservative conversions?
Answer: Orthodox Judaism sees Conservative Judaism as illegitimate because Conservative Judaism does not believe in the divinity of the Torah "as they do." Thus, they believe that Conservative Rabbis are not as qualified as Jews "of honest and authentic faith" to supervise a conversion, sit as a court that judges the qualifications of the candidate, and sign/witness the documentation of the conversion.
Once I told an Orthodox Rabbi that I did accept "Torah from Sinai". He said that he did not believe me because I had attended a Conservative school. I asked if he would believe me if I told him that I was independent of their teachings. He said that he still didn't believe me and feared I was just trying to trick him.
I wish my Orthodox colleagues well. I can't bend my heart and soul and mind to fit their categories when they don't even accept each other! I'll continue to teach anyone who wishes to come and study with me - and they thereafter can choose how they wish to live their lives as Orthodox Jews or not.