Hi, I am running into an error when trying to build the merger tree database for a dark matter only unigrid simulation. The error is as follows: //turing/home/tszkali2/yt-ppc64/src/yt-hg/yt/analysis_modules/halo_merger_tree/merger_tree.py:27: DeprecationWarning: the md5 module is deprecated; use hashlib instead import os, glob, time, gc, md5, sys yt ERROR 2011-02-15 17:22:56,701 Couldn't figure out output type for DD0025/DD0025 Traceback (most recent call last): File "MergerTree.py", line 25, in <module> MergerTree(restart_files=files, database=my_database) File "/turing/home/tszkali2/yt-ppc64/src/yt-hg/yt/analysis_modules/halo_merger_tree/merger_tree.py", line 186, in __init__ self._run_halo_finder_add_to_db() File "/turing/home/tszkali2/yt-ppc64/src/yt-hg/yt/analysis_modules/halo_merger_tree/merger_tree.py", line 219, in _run_halo_finder_add_to_db self.period = self.pf.domain_right_edge - self.pf.domain_left_edge AttributeError: 'MergerTree' object has no attribute 'pf'/ Does anyone know why it "couldn't figure out output type for DD0025/DD0025"? I load DD0025/DD0025 separately it is just fine. The script I used is just the basic one from the online documentation: /from yt.analysis_modules.halo_merger_tree.api import * # Pick our snapshots to use. files = [] start = 25 finish = 320 for i in range(start, finish + 1): files.append('DD%04d/DD%04d' % (i, i)) my_database = 'halos.db' # Build the tree. MergerTree(restart_files=files, database=my_database) / I am using yt v2.0 and enzo v2.0. Thank you very much for answering my question. Cheers, Tsz Ka