FM to Identify Incidents Locked to a Problem

Hi Gurus

I'm not sure if this should be in the ABAP Forum or here,...but I'll start here anyway.

I need to programmatically identify if an Incident is Locked to a Problem.

Currently we have an interface which updates Incidents, but some of these updates are failing because the Incident is Locked to a Problem Transaction and therefore no updates are allowed on the Incident, only the Problem can be updated.

I've tried using Function Module CRM_ORDER_READ, which gives me the the Document Flow linkages, but I cannot see within that data set if the Transaction is Locked to the Problem, unless I'm missing something.

Does anyone know if it is contained in another variable within CRM_ORDER_READ, or is there a separate Function Module I can use.

Many Thanks in advance

Panduranga