Error: Assignment of Context Object is Incomplete

I am experiencing a rather odd problem in PI 7.1 SPS 7 - I am unable to add a context object to my Service Interface.

First I create an xsd:string context object called "JobNumber".

In the same SWCV, I open my service interface. (abstract, stateless XI 3.0 Compat, asynch) and click the "Context Object" button. In the Context Object Assignment screen, I navigate to the appropriate node in my schema and assign the context object. When I save & activate the changes to my service interface I get this error:

Check Result for Object SynchIncident 
Check of operations for service interface 
Check of operation SynchIncident 
Assignment of Context Object OMS_JobNumber | http://oge.com/ccs/order is incomplete

Furthermore, if I click the button "Check and Correct Assignments for Context Objects" PI removes the context object altogether.

Operation 'SynchIncident': 
Assignment of Context Object OMS_JobNumber | 
http://oge.com/ccs/order is redundant and will be removed

Any suggestions for resolving this issue?