Matt white paint all patchy

Hi,

I am in the process of painting a few rooms all re-plastered.
Bought some Trade Leyland matt white emulsion.
Did undercoat with a mix 50% emulsion 50% water and all went very well. Next day 1st proper coat, no problem and then my 2nd coat ended up in a disaster. The walls against the light look all patchy, it is like each strike of roller has marked the walls.
Tried to have a 4th coat with a different roller, same.
Looks awful, like a kid has decorate the house.

What is due to?

How can I fix it?

Have done another wall re-plastered with a silk paint different colour and I had a nice finish. Is it just the way Matt paint is?

(Going back to my silk now, I hope to have lots of answers before the end of the day as I need to move on).

Thanks to tell me.
Letty

 

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