Gap in Model (Blender)

[docdo1]

As you can see below, there is a little 'gap' in my model which is causing annoyance.
The vertexes are joined and I really don't know how I can fix this, any help will be appreciated.
(Sorry about the size of them.)

[IMG]http://i.imgur.com/O5JLGmz.png[/IMG]

[IMG]http://i.imgur.com/JH5u2Up.png[/IMG]

[IMG]http://i.imgur.com/iALDnHV.png[/IMG]

[Jeff_epic_mopeds]

The left ones are joined, but the right two aren't.

[docdo1]

[QUOTE=SergerantJoe;45860863]The left ones are joined, but the right two aren't.[/QUOTE]
How would I go about fixing it then?

I select the verts and hit 'J' but the neck still had no change in its slit.

[rHebKo]

Select the verticies in edit mode and press alt+m to merge them