Chemistry is one of those intangibles you can't predict. When a News Director puts co-anchors and anchor teams in place, he has no idea if those pairings will click or not.
And even the best anchor in the world can look average when paired with the wrong people.
A few years ago I had a client who was very talented, but couldn't get any decent cross talk with her co-anchor. She was loaded with personality and he made Jim Lehrer look like an extrovert. Luckily she managed to get some decent chatter going with her sports and weather anchors.
Very often a problem like this one is caused by pairing people who have little or nothing in common. And when this happens, you can get handed what is known as a "dead fish" in the middle of a newscast. That's when another anchor makes such a bizarre toss that you have no way to come back, as if someone handed you a dead fish and you say, "What the hell am I supposed to do with this?"
I've had this happen to me a few times, as we had an anchor who liked to hand off with lines that made absolutely no sense.
So, bottom line, you need chemistry and no dead sea creatures.
Sometimes chemistry is natural, as you connect with the people with whom you're anchoring. But sometimes you have to work at it.
The easiest way to do it is the most obvious. Get to know the people you're anchoring with. Go to lunch or dinner, spend some time together off the clock. (I'm not suggesting you date anyone at the station, which is usually a huge mistake.) And if you can't spend time together away from the station, take some time to talk during working hours about stuff that has nothing to do with news. Find out what your co-anchor does off the clock, wander back to the weather and sports departments and shoot the breeze.
The better you know the people you work with, the better your anchoring will be. Viewers can tell if the people on a news team actually like one another, and so can your future News Director.