Drip irrigation pressure puzzle

I have a couple of drip lines each about 15 feet in length. Some emitters are installed directly in the main line and others are on short lengths of 1/4 " tubing that then attaches to the main line.
I'm having trouble regulating the pressure. The small pressure regulator I bought seems to have no effect and it's easy for me to get fountains of water spurting even from 1/2 gallon per hour emitters. I don't think that's what "drip" irrigation is supposed to do.
Most puzzling is that in one line I noticed that little water was coming from an emitter about half way down the line, even though all those beyond it were doing well. So I pulled the emitter out of the tubing and the flow through the hole did not seem much different from the flow through the emitters.
I'm looking for suggestions about how I might get this to work better. Thanks for your attention.
Tom
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We really need to know what kind of drip lines you have to make informed comments.
Some pressure regulators have minimum flow rates. Below that flow rate they don't reduce the pressure reliably.
snipped-for-privacy@yahoo.com wrote:

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One should never connect the drip line to the main line. The drip line should be connected to a sub-main line and the water flow to this sub-main line can be controlled by fixing a control ball valve. In existing circumstances you may use pressure compensating emitters which emit a calibrated amount of water irrespective of the water pressure in the main water line or land having un-even contour. For more information you may write to snipped-for-privacy@gmail.com Girish
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