bond creates a new bond between two selections, each of which should contain one atom. You can easily create a new bond by selecting two atoms, each with the CTRL-MIDDLE-MOUSE-BUTTON and typing "bond" on the command line.
bond [atom1, atom2 [,order]]
cmd.bond(string atom1, string atom2)
The atoms must both be within the same object.
The default behavior is to create a bond between the (lb) and (rb) selections.