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
---------------------------------------------------------------