You are drawing vector style, but illustrator won’t snap to the anchor points. You tried over and over again and you are on the verge of molesting your hardware.
If your Adobe Illustrator paths won’t snap, check these settings:
Align to pixel grid
Select all your paths. In the Tranform paths, use the tiny triangle to get to the Options. Deselect ‘Align to pixel grid’.
Align to pixel grid of new objects
Now you freed your existing objects of the influence of the pixel grid, but newly created objects still inherit this frustrating property. To also free new vector objects from the spell of the pixel grid, invoke the Transform Options palette again and deselect ‘Align new objects to pixel grid’.
Snap to Grid
In the View menu, make sure that ‘Snap to Grid’ is unchecked (SHIFT-CMD-‘). Toggle the visibility of the Grid with CMD-‘. The size of the Grid can be adjusted in the Preferences panel.
Snap to Point
Make sure that, in the View menu, ‘Snap to Point’ is checked (ALT-CMD-‘).
You can turn Smart Guides off and on in the View menu (CMD-U). These are the visual aid lines that pop up on the spot. They show guides to all anchor point that you pass within a 2 pixel range of a 0, 45 or 90º angle.
However, this Terminator-view doesn’t influence the ‘Snap to Point’ behaviour.
Overruling Smart Guides with the Command Key
Per default setting, Illustrator’s Smart Guides try to find and show alignments between all anchor points of the path you are dragging and all anchor points of other paths. Not just the anchor point you are dragging around. Smart Guides can easily get in the way of a simple Snap to Point. Specially when these ‘distant’ Smart Guides overlap within the 2-pixel-snapping zone of the ‘primary’ anchor points you are trying to snap together. (It’s perfectly normal if this makes no sense at all to you, unless you have encountered it. Really, it’s not you.)
All those crisscross emerging Smart Guides can be temporarily overruled by holding down the CMD key. It’s that simple, once you know it.
Other tips when illustrator won’t snap.
Check the Preferences panel for more settings of the grid, degrees of the angles alignment, the snapping range in pixels, units and more.