Having problems with snapping lines in 3D view

[Anonymous]

Hi,

I want to make several elements snap together in 3D view as I can't do it in 2D, but only a few of parts actually snap. It's weird because they were all created in the same way but only the odd one or two will snap onto each other.

Attached is a screenshot of what I want to snap, the red line indicates where the join is.

Thank you for your help

[Anonymous]

Hmm I'm getting desperate now . Please can someone help me