You are selecting curve 1 and shift selecting curve 2 and then selecting edit curve/attach? I ask because it looks like you are trying to open/close.
Also, try reversing the direction of one of the curves before attaching. Make sure they are not in a group with some kind of history.
(1) curves before attach
(2) curves after attach with blend option
(3) cureve after attach with connect not multiple knots option
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 10-10-2011 at 04:15 PM.