Hi, I tried to run a workflow with the API, but get an Error 500 when I try to run the WF...The paster.log shows the following error... $ workflow_execute.py 92cc01ed93dc0f0fc91e3ded35497c0a http://srp106:8080/api/workflows ebfb8f50c6abde6d 'TEST the API' '1=ldda=7c5ebce002fc9d5c' Paster.log galaxy.web.framework ERROR 2012-02-21 14:36:33,067 Uncaught exception in exposed API method: Traceback (most recent call last): File "/home/tdeboer/code/galaxy-central/lib/galaxy/web/framework/__init__.py", line 145, in decorator return simplejson.dumps( func( self, trans, *args, **kwargs ), indent=4, sort_keys=True ) File "/home/tdeboer/code/galaxy-central/lib/galaxy/web/api/workflows.py", line 123, in create hda = ldda.to_history_dataset_association(history, add_to_history=add_to_history) AttributeError: 'NoneType' object has no attribute 'to_history_dataset_association' 172.16.108.6 - - [21/Feb/2012:14:36:32 -0700] "POST /api/workflows?key=92cc01ed93dc0f0fc91e3ded35497c0a HTTP/1.1" 500 - "-" "Python-urllib/2.6" Any ideas? Also...I had a hard time finding out what I should use for the dataset source parameter "src" in "step=src=dataset_id" and just tried ldda, but would hope there is a little info on what this hda and ldda is? Thanks, Thon