I just can't

People have told me to be positive and encourage team mates to do a little better and i can win games in bronze. They have told me to play champions that I am really good at. Last game pissed me off so much I am almost in tears. I decided to play vel koz. I am usually somewhat toxic but the entire game I was positive and said GJ to people. Our lineup was mundo support, varus adc, quinn top and skarner jungle. I dominated lane ending up about 11/1 by mid game. Quinn fed nocturne @ top which I hadnt noticed until the team fights came. Skarner wen't full AP/Attack speed. When it was team fight time I repeatedly told them to jsut peel for me and I can kill them off. First nocturne ult on me, everyone runs away chasing the almost dead morg while being killed by the rest of the enemies. After telling them for the last time to peel for me, the skarner began getting mad at me for being "toxic". Mundo just said he tried to peel for me. By the end of the game, what a surprise, I lost! Honestly it just seems like the odds are always against me. I have no idea what to do. I've tried duoing and the same crap happens, my duo partner even calls me bad luck. Here's the score partway in. http://imgur.com/3ZtqGBc