Patchy Paint

[Nightowl003]

I have patchy looking painted walls, all walls are effected although the walls that have direct light on them are most noticeable.

Preparation
Walls washing down with sugar soap.

Equipment
9" B&Q roller 1st & 2nd coats.
9" Purdy Colossus roller 3rd coat.
Dulux Once Mat Emulsion - Almond White

Room ventilated, mild day & heating not on.

I got incomplete coverage with the first coat, I don't remember whether it was patchy probably cause I was distracted by the fact it didn't do what it said on the tin!
The walls didn't get a 2nd coat for 24hrs. I added a small amount of water to make paint less thick. It achieved complete coverage but dried very patchy.
Having read several posts on this forum I put this down to type of paint & user error (going over areas more than once and delays whilst refilling roller tray etc)
The 3rd coat was applied using new roller, ensured generous application of paint & taking care not to go back over areas already covered. The 3rd coat is now dry & still appears patchy

Any suggestions/advice on how I can get rid of the patchy painted walls and products I should used would be very much appreciated.

Nightowl003

I've done a far bit of decorating over the years and never had this problem before.

 

[Robbie uk]

It could be the Dulux Once. I usually thin this down and do two coats as the one coat is a bit thick and in my opinion doesn't cover very well. That's how they get it to cover... because its like treacle !!