YOU ARE USING TOO MUCH PAINT AND PRESSING TOO HARD ON THE ROLLER.
I'm a little surprised nobody else pointed this out so far. Essentially, the roller is like a boat cutting through water, and the roller marks are the wake of the roller left behind. The harder you press, the more you squeeze out of the roller and off to the side, and thus the bigger the wake/roller mark. The more paint to push out of the way, the bigger the wake.
One way to eliminate the problem is to use flow-control agents that increase drying time so the paint has more time to level out. But then you still end up with more paint on the wall than you need. All paint manuals and brands advise that two thin coats are better than one thick coat, and this is one of the primary reasons why: it goes on better.
I ALWAYS get roller marks while rolling the paint on from a freshly-charged roller. Then, after the roller runs out of paint, I gently roll back over the parts I just painted with an uncharged, "dryer" roller to collect the extra paint and spread it out more evenly on the finish roll to eliminate the roller marks. The final run is always with a much lighter touch than the first few strokes. Also, make sure every final stroke is in the same direction for a more even sheen.
I have always done my own painting. I usually use Pittsburgh Paint, or Dutch Boy. I never encountered streaking until just recently. I purchased Glidden paint with the primer. The only thing I came up with is that it is a much thicker paint. it has a little bit of body to it, so it holds on to it's "shape". You have to be very careful not to leave any thicker paint behind. The Dutch Boy I painted with recently, also with primer (no streaks) is pretty watery looking, but covers beautifully..and no streaks. So I believe that is something that occurs with thicker paints.
06:29PM | 03/02/16
i feel your pain, as I have had the same issues with Behr paint. I have painted many a walll and ceiling and never had this issue. I bought the 2 gallon pail of ceiling paint and had it mixed for polar white and all it did was streak. I am now on coat #4 and have to sand the ceiling and start all over again.
05:20PM | 06/15/16
I just did a ceiling with Behr ceiling paint, when the sunshines through the window there is nothing but streaks, the other ceilings came out good. I was disgusted, didn't press hard, plenty of paint on roller. I still cannot understand how flat paint can leave streaks after 3 coats. I have painted many ceilings successfully. I told the owner I did my best, and not sure what the problem is.