RTC API usage. Can't find attachments in a child project area with unconfigured process template

A java program update the state of a work item created in a child project area (unconfigured process) which reuse the process template of a root project area  (RTC 4.0 scrum process template).  It works on the root project area.  It is a custom workitem type.

Error: SEVERE: Error while retrieving image: processattachment:/workflow/transfer.gif
Throwable occurred: com.ibm.team.repository.common.ItemNotFoundException: CRRTC0317E: Could not find ProcessAttachment for path: _0PQbsAe1EeKiHO3ea305vg/workflow/transfer.gif
    at com.ibm.team.workitem.service.internal.ImageContentService.findProcessAttachment(ImageContentService.java:156)

Program which does not work:
    private static String changeStatus(ITeamRepository repo, Integer workItemId,
            Boolean buildStatus, String actionOK, String actionKO, IProgressMonitor monitor)
            throws TeamRepositoryException {

        IWorkItemClient client = (IWorkItemClient) repo
                .getClientLibrary(IWorkItemClient.class);
        IWorkItemWorkingCopyManager copyManager = client
                .getWorkItemWorkingCopyManager();
        IWorkItem wi = client.findWorkItemById(workItemId,
                IWorkItem.FULL_PROFILE, monitor);
        if (null == wi) {
            return ("work item " + workItemId + " cannot be found");
        }
        IDetailedStatus status = null;
        String actionName = buildStatus ? actionOK : actionKO;
        try {
            copyManager.connect(wi, IWorkItem.FULL_PROFILE, monitor);
            WorkItemWorkingCopy wc = copyManager.getWorkingCopy(wi);
            IWorkflowInfo wfInfo = client.findWorkflowInfo(wi, monitor);
            Identifier<IWorkflowAction>[] actionList = wfInfo.getActionIds(wi
                    .getState2());
            String actionId = null;
            for (int i = 0; i < actionList.length; i++) {
                Identifier<IWorkflowAction> action = actionList[i];
                String name = wfInfo.getActionName(action);
                if (name != null) {
                    if (name.equals(actionName)) {
                        actionId = action.getStringIdentifier();
                        break;
                    }
                }
            }
            if (null == actionId) {
                return "Action not found: " + actionName;
            }
            wc.setWorkflowAction(actionId);
            status = wc.save(monitor);
            if (status.getCode() != org.eclipse.core.runtime.IStatus.OK) {
                return "Error: " + status.getDetails();
            }
        } catch (Exception e) {
            return "Unexpected error: " + e.getMessage();
        } finally {
            copyManager.disconnect(wi);
        }
        return null;
    }

Any help would be greatly appreciated.

Thanks