I'm puzzled...I sketched a 2D curve in a Skeleton part and then used ECG to show it in a piece part (a section of pipe in this case which is part of a subassembly). I'd like to just sweep a thin circle along this curve to create my pipe but it says "Specified trajectory is not valid. Please reselect". I have read this TPI ( This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.