Harrased

I work at a media company. I am a traffic producer. I research and write the traffic reports heard on radio and tv stations. One of the reporter there seems to have a vendetta against me. I have never done anything to provoke him but he continually tries to find ways to get me into trouble at work. We are supposed to work with one another to get accurate information. If he believes I am wrong he doesn't come and tell me. He will try and find the correct information and not inform me of his findings. Then he will either tell and/or send an email to our manager and boss. Then I am confronted with this problem from my manager and most of the time I make my point and I am in the right. Of course, sometimes I am not. But at the same time I was not made aware of the mistake I was making at the time so I don't have a chance to fix my mistake. This keeps happening over and over again. I don't have a problem with anyone else in the office but him. This keeps happening more often as well. I feel like he wants to get me fired. My manager, who is a friend of his, also keeps defending him. My immediate superviser is on my side but I don't know what to do about it. I dread coming into work and making a mistake because he is waiting for me to do something wrong. I feel harrased but I don't know if it technically is. Please help me.