This is a tough one to address, even if we could see a problem picture.
Reflective meters are simply not 100% accurate. It is not "wrong", but what the meter will read depends on the scene (which varies). The sooner this is realized, the better. There is absolutely nothing new to be covered here, but if anyone doesn't know yet, they should look into it.
Reflected meters are aimed at the subject from the camera, and meters the light that the subject's colors reflect.
A white background or subject reflects a lot of light, which reads high,
so the meter underexposes the picture.
A black background or subject reflects little light, which reads low,
so the meter overexposes the picture.
The expected reflected goal is that all results come out middle gray brightness, not too dark, not too bright. This is all the meter can do (it cannot recognize anything). Fortunately, many typical scenes contain a random mix of dark and light colors that probably will average out about middle gray, then the middle gray result can often be about correct. When otherwise, we can compensate it, to correct it to come out as as we want, brighter or darker, as needed.
Incident meters are the reverse, aimed at the camera from the subject, which reads the incident light from the light source directly (is never influenced by the "subject"). So then any subject tone, be its colors light, dark, or middle, is shown as it is. Kind of a big deal. Point&shoot, where it counts.
Incident meters have the accuracy that newbies imagine their reflected meters ought to have (but can't). Of course this is not possible at the camera, incident meters meter the light incident on the subject (from the subjects position).
To illustrate Reflective metering is this obvious example:
How light meters work - Simply how life is. If we imagine our meter should always get it right, we're in for disappointment. Which is our fault, we need to learn what to expect, and how to react.
Matrix metering has a computer in there doing unknown things. It is far from a human brain, too dumb to recognize the scene with any human understanding. It cannot tell a black cat in a coal mine from a polar bear on the snow. BOTH will come out around middle gray (reflected meters). Matrix does try point&shoot heroics, but it is also safe to say we are never sure what it will do.
Matrix Metering result will also vary with subject contrast, and is heavily influenced by area under the focusing point. With single point focus, you should know where that is. With Dynamic or Auto Area, you may not know.
Quoted from the
Nikon Glossary online, which says:
Matrix metering:
If you are a beginner, Matrix is where you should start. As your skills grow, and they will, you will acquire a better understand of when it might be beneficial to use other light metering options.
Center metering: Meter sensitivity is biased toward the center of the viewfinder.
Recommended when the subject is in the center of the picture.
Spot metering: A metering method in which meter sensitivity is concentrated within a small circle in the center of the viewfinder. Recommended for very precise metering;
requires extensive knowledge of lighting for really effective use.
Me? I don't care to participate in all that newfangled unknown point&shoot stuff, trying to guess what it might do. When possible, I always use Center Weighted metering and Single Point focus (old fogy stuff), because I can see the scene too, and I like knowing what to expect that metering will do. I still have to deal with the reflective meter, but we learn, and Center and Single are simply easier to understand.
But metering is a skill that we learn.