I am trying to add a flange edge to the top of the cylinder from the images. The machine shop I talked to starts with the blank sheet metal round and start forming the cylinder by pushing it with a wheel on a lathe. They form the flange at the end by (basically) by leaving it alone (not pushing it with the wheel). I am trying to add this flange to the top of the model. Holes will go there that will attach to other pieces. For some reason, when I click on "Edge Flange" and try to select either of the circumferences at the top, it wont select them (nor will it let me know why). My thought is that I'm doing something wrong but I am not sure what. I've attached pictures of the part. Thank you for the help.
Machine shop using method similar to this one: