OpenGL rendering with VBO's is quite confusing. Seems like you're mixing things up.
You're missing a glBufferDataARB(). That function is used to fill the buffer with data.
In your code, you send the vertex data to the draw call, which is wrong. The fourth parameter of glDrawElements is a pointer to the array of indices.

This tutorial shows how to use VBO's to render indexed geometry. For lines, you don't really want indexed geometry so you have to dig a little further yourself. Check out this tutorial:


http://www.songho.ca/opengl/gl_vbo.html

Also have a look at their vertex array's tutorial. That may give you some ideas about the differences between VBO's and vertex arrays, because people confuse those two often.

Good luck.