Hi all yt-users, I'm running into a simple problem I think, but can't find the correct documentation. I want to make a slice plot of dark matter density with velocity vectors overlaid, using Gadget HDF5 data. I have uploaded my script here : http://paste.yt-project.org/show/5347/ The slice plot works fine. However, I got an error message for the velocity overlay: http://paste.yt-project.org/show/5349/ The bottom line is the following : YTFieldNotFound: Could not find field '('all', 'velocity_x')' in snapshot_000. The error is pretty obvious, I think YT is looking for the default field, whereas it should look for a deposit of the dark matter data. Somehow I should specify that yt should look for this deposit, but I don't know how ? Thank you by advance for your help, Long -------------------------------------------------------------- Long DO CAO (Office F617) Office phone: +81 6-6850-5482 Osaka University, Graduate School of Science Department of Earth and Space Science 1-1 Machikaneyama-cho Toyonaka, Osaka, 560-0043, Japan ---------------------------------------------------------------