Can't notice the breath I can't find the breath (sometimes I can, but the majority of the time I can't) 


I can't notice the rising and falling of the stomach even when lying and putting my hand on it and also to notice the breath in general is very hard for me.


Now I understand I can say if I don't notice it "knowing" or "breath" etc - but then I wait and wait and nothing - and in the mean time lots of secondary objects come up. If I follow them though its not good- because you should have a primary object to build concentration, so I need an "anchor" 

So when I say "knowing" and then what should I do? Just focus on my belly? And if i don't feel anything? Not even in other areas like the nose - what should I do - focus harder? Follow secondary objects only? 

I have practiced for a long time now (did retreats etc) and I thought this problem would fix itself, but I still have this problem. When I meditate I do 1 hour walking, then 1 hour sitting (mahasi style).
Hmmmm... interesting. Try this: do controlled breathing for a dozen breaths (count breaths on fingers and do a moderately-slow deliberate breath-ins and breath-outs), then for a dozen breaths let the breathing happen on auto-pilot (keep counting on fingers. I assume you have twelve fingers LOL).

When you breathe deliberately you can't possibly NOT notice the breath, right? After all, at that time you are deliberately using the muscles of the chest and diaphragm to suck air into your lungs. So you should feel yourself pulling pulling pulling not too fast, slowing down, then stopping, holding a little, then going down and out out out not too fast, slowing down again, a tiny pause. It is what you yourself are doing, so you can't miss it, right?

Then when you let it happen naturally, the same attention you used for deliberate breathing should continue on to natural breathing.

Also, do you sit in Lotus / Half-lotus? Try sitting in Vajrasana - it arches your back a little more and forces to open the chest and diaphragm. Perhaps (I don't really know but I'm guessing) your breathing is too shallow because you are in the habit of blocking your lower abdomen? Vajrasana is a good posture for this kind of practice, to penetrate the lower chakras.