Vertex Tool issue

I am trying to shape a brush to a specific look, and when I do, this is how it should look:

http://prntscr.com/fudmu4 (Grid Picture)

But this is how it turns out:

http://prntscr.com/fudne8

http://prntscr.com/fudnlu

It then prompts me with nothing in-game, an error, or when I restart the SDK, a message saying it must remove an invalid brush.

If anyone can help, i'd really appreciate it, thank you.

Quote from FMPONE

Just now, FMPONE said: You can't have convex shapes (a box that goes in on itself). Cut that brush horizontally everywhere you have it going inward.

I understand, let me try that, thank you!

Quote from FMPONE

On 7/11/2017 at 7:10 PM, FMPONE said: You can't have concave shapes (a box that goes in on itself). Cut that brush horizontally everywhere you have it going inward using the cut tool.

edit: concave, not convex. How embarrassing.

Update: I got it to work!

Thanks for the help FMPone, I really appreciate it

Quote from JorisCeoen

On 7/11/2017 at 8:04 PM, JorisCeoen said: Ah... the endless concave convex confusion. It took me a few months understanding the concept. But yea, you can't have any concave shapes in Source, not on brushes (and as such on brush displacements) or even collision models. Basically anything that forms a solid shape to block players from passing through). Only exceptions are, of course, models, and after having converted a convex displacement, the mesh itself. However sometimes making complex concave shapes from displacement meshes can cause lighting issues... but it's generally not a problem.

Thanks for the help, i'll make sure not to forget that