i want to attach a line (wire object) with a box (rigid object).if the box moves the line moves with box wherever box goes.I used all the attach command under the wires shelf, but no succes.Can anybody explain it step by step?Thank you.

create RBD and Wire objects through shelf (or manually)
press Attach Wire To Surface Shelf tool
follow status bar steps to complete
(in short they are
select wire, Enter
select points to attach, Enter
select rbd, Enter
select points on rbd (optional), Enter
)
it will be spring constraint by default so either tweak its stiffness or change it to Hard

and there is this…
http://ihoudini.blogspot.ca/2011/10/wire-to-rbd-feedback-in-dops.html [ihoudini.blogspot.ca]