missing "RESERVED" BPM-Tasks from my Substitute in Taskcollection BPM OData

Hello,

i'm developing a Integration-scenario with BPM-Tasks. Therfore i'm using the ODATA-REST Service.

The access to the Taskcollection shows me all my BPM-Tasks.

Now a second User activated me as his substitute. I expected that my TaskCollection shows me all the Tasks of my substitute, but he just delivered me the tasks that are in statuts "READY". The Tasks which are in status "RESERVED" were not shown in the TAskCollection.

Has anybody an idea, what i have to do for getting all Task in every status.

this is my request for the TaskCollection:

http://xxx:99999/bpmodata/tasks.svc/TaskCollection?$orderby=CreatedOn%20desc&$filter=Status%20ne%20%27COMPLETED%27&$expand=TaskDefinitionData&$inlinecount=allpages

There is one more Problem with the TaskCollection:

The propertie "SubstitutedUser" is always initial, even when the Task is from the Subsituted User by activated substitutionrule.

I'm thankfull for every idea.

Regards

Demetrius P.