Why won't my model unwrap? For some reason, my model won't unwrap.
I have uploaded the model here: http://www.pasteall.org/blend/37735

One thing that surprises me is that if I try to select a ring, the ring stops at a certain vertex:



I have extended the ring manually, then clicked "Mark Seam", then I selected the upper lid and the lower lid of the barrel and also clicked "Mark Seam" for each of them.

When I now click 'u' and then 'Unwrap', nothing happens. I have been able to unwrap other models, but not this one.

Does anybody see where I might have missed something? Blender does not show any error message, it just doesn't unwrap.

Thank you for the help.

Edit: I have uploaded a new model here to reflect the suggested changes: I removed all doubles, I applied rotation &amp; scale, and I put the same in a location where Blender could select a whole ring automatically.
But it still won't unwrap:

http://www.pasteall.org/blend/37739

Edit 2: Now here is a simpler model without the handles. It is really absolutely simple geometry (I think), but it still won't unwrap:
http://www.pasteall.org/blend/37741

Could anybody have a look again? Thank you!
I think it is impossible to select the whole edge using Alt+RMB. It is a matter of geometry you've got there.
 What you can do is select the upper edge/vertex and then (while holding the Ctrl button) the bottom one.


You may also select the upper vertex/edge, then (holding Shift) the bottom one and then go to Select-->Shortest Path.


QUICK TIP: I figured out that your origin point is located outside the mesh. It is a good habit to keep it inside. Being in Edit Mode select the whole mesh (A), press Shift+S-->Cursor to Selected and then (being in Object Mode) Shift+Ctrl+Alt+C-->Origin to 3D Cursor to place an origin point inside a mesh.


Note: You'll probably have to delete the top and bottom ngons to make a proper unwrap. And make sure to remove the doubles (being in Edit mode select the whole mesh [A]), then press W-->Remove Doubles).

EDIT: I've unwrapped a mesh and the UV islands look like this:


Here's the .blend to download:
http://www.pasteall.org/blend/37742