Can't get ctr B (Bevel) to work on guitar hardware

I am doing a tutorial here: On a certain piece of hardware I’m supposed to select two loops and press ctr B to bevel and one click on the MMB to add an extra loop for a better bevel. I can’t get a beveled look to the shape I am supposed to bevel. Can someone tell me what I am doing wrong? It’s a very minor piece of the guitar, but I want to learn the technique. I used the bevel (ctr B (bevel) earlier in the tutorial to make a screw. That was no problem. But for some reason, it’s not working on this little knob.

This is after I select ctr B and roll MMB once:

This is the result:

Link to Blender file:

Note: This is the second time I’m posting this. I don’t see my previous post.

First remove any double vertices by selecting them all and W / remove doubles
In object mode try Ctrl+A / scale to clear the objects scale.
When you bevel you may want to hold down the shift key when dragging the mouse so you have finer control of the bevel since your object is quite small.

Instead of using the mouse yo could always start bevelling then either LMB. Then you can change the bevel and segments in the bottom of the toolshelf (T) or pressing F6

Remove those 2 inner edge loops one by one (X>edge loop), then recalculate normals (Control+N) and make that bevel.

I remade the whole object. I did the ctr A scale in object mode and was able to make the bevel this time. Thanks.