I have a part with a shelled loft (curved and tapered), and I've cut away one wall at a large radius. I need to add a series of lugs with tapped holes along that cut to attach a cover. The first lug went in OK, but when I try to create a 3d curve driven pattern I get the message "Unable to create this extruded feature due to geometric conditions."

The lug is an extrusion "up to next". I've tried making it blind, but that doesn't help. Any ideas? "Due to geometric conditions" is so vague as to be just about completely unhelpful.