Not getting full amount of Street Passes at Nintendo Zone.

For the past few days I have been getting THREE and only THREE Street Passes per Nintendo Zone.

My friend has been going to the same nintendo zones as me. He has been getting 6 per zone.

I  know it has nothing to do with me possibility already in the Nintendo  zone, I went to a few new Nintendo Zones last weekend, still only got 3  street passes.

My error has nothing to do with some times getting 1, 2, 3, 4, 5, or 6  street passes. I am getting no more then 3. I am getting 1s and 2s. But  never more then 3.

My friend goes into a Nintendo zone with his 3  3DSs, gets 6 per system. I follow behind him, I get 3, nothing higher. So it is not like  there is no one in the zone.

As anyone been experiencing this? There is something obviously wrong with my system.