What do you mean I'm doing it wrong?
I remember a particular job that I had for a grand total of two weeks. I was capable of doing the job. It was a hard job, but not impossible. I didn't get fired, I quit. Why did I quit? Because my boss didn't communicate what was expected of me both in performance and scheduling. I did the best I could with the information I had, but it got to the point where I was being condemned for not doing things I didn't know I was supposed to do, and didn't show up when I was supposed to show up because no one told me to. In Malachi 3 there is something similar going on. "How have we robbed you? How have we spoken against you?" The people were ignorant. The difference between my situation and theirs was that they had God's word and the prophets telling them exactly what was expected of them, and they chose to at best ignore it, at worst pervert it. We have the word. We have great Bible teachers. We have Christian bookstores, radio, television, and internet. We are without excuse. Get into God's word. Get God's word into you. Get into the world and show them what it looks like when someone has the word and the Spirit of God in them.