Comment 7 for bug 446591

Yes for me it is one volume, too, but the solution works.
I just needed to change in a similar way, and at the end of the rows there was an additional lvm_... or something, and that stays unchanged.
so it should be something like:

>> There you will see something like
target=sda5_crypt,source=/dev/disk/by-uuid/blahdiblah,key=none

Change this to:
target=sda1_crypt,source=/dev/sda1,key=none, lvm=root
target=sda1_crypt,source=/dev/sda1,key=none, lvm=swap (dont know the exact syntax of the lvm thingy)

But that did work for me.