Why can't I see the target marker when approaching another craft?

[Enrico shark]

I've been trying to do some rescue missions in the career mode. The problem is that it's very hard to spot the other craft, especially when you're in the dark side of the planet. As I saw in the Scott Manley's tutorials about Rendezvous, he has a yellow marker around the target when you have the visual set on your craft, not in map mode, and the marker also says the distance from the target. Without it, I have to keep changing from map mode to the craft to try and spot the target. 

Thanks in advance

Enrico

[Rodhern]

Press F4 to get the target diamond. Double click the diamond to turn it green (targeted).

[Enrico shark]

4 hours ago, Rodhern said:

Press F4 to get the target diamond. Double click the diamond to turn it green (targeted).

Thank you very much!