Agent assignment/exclusion

[Lynn Dorling-Williams]

Hi all,
I have a problem workflow on SAP 4.6c  where the agent has been sent a
workitem, but then can not action it.  The error message says "The agent is
excluded from performing the task".  He has not been excluded according to
the role resolution set on the task.  Has anyone come across similar
inexplicable problem?  Are there other error causes that give this message?
After this task fails, the next step loses its capability to assign any
agents at all.
 
I am working in SAP release 6.10.    I have checked user authorisations and
there is no problem there.  The task is a general task.
 
This is a simplified (honest!)  run down of the workflow and related
problems:
Invoice approval wf - (1) trigger (2) pop to enter cost centre (3) role
player determination (4) certify user decision with deadline  (5) authorise
user decision with deadline
(6) Post invoice   ----------------- if deadlines are triggered the
original wi is set to obsolete and new wi's created.
 
The workflow uses BUS2081 and associated sub type. Step (3) finds positions
for use in the WF by looking up invoice value and cost centre mapping in a
Z table, and then outputs to the wf container - Certifiers, Authorisers,
also for dead lines DLCertifiers and DLAuthorisors and if problems ADMIN
(WF administrator).
 
Problem example:
Workflow initiator is "Sally"
On the certify step Dave, Tom and John are identified as holders of
identified position and therefore sent wi's.  Dave carries out this step
(general task, no excluded agent)
On the workflow step for  authorisation of the invoice Dave and Tom are
identified as holders  of position and therefore selected agents.  Dave is
excluded because he was the actual certifier (excluded agent  on decision
tab of  authorisation step).  When Tom tries to action workitem the log
records an error message "The agent is excluded from performing the task".
 
When I  view the agent assignment on the workitem, the excluded agent is
Dave and possible agent all users, however the selected agent is blank.
Because this workitem did not complete within the deadline, the workflow
logically deletes this workitem and then creates 2 new workitems, 1st
should go to Tom and the other goes to Phil.  These workitems were created
but with NO agents assigned.
 
I can not duplicate this problem in Dev environment, and an now stuck.   I
can't see any reason for Tom to be excluded and can't figure out how/why
agents were not assigned to subsequent step.
 
Thanks for your patience
Lynn