Set Lookup value in USD Action Call ?

Hi ,

I need to set the lookup value during the Creation of Case in Action Call for USD.

LogicalName=incident

customerid=EntityReference([[$Context.InitialEntity]],[[$Context.Id]])

customeridname=[[$Context.firstname]] [[$Context.lastname]]

new_contactid=EntityReference([[$Context.InitialEntity]],[[$Context.Id]])

new_contactidname=[[$Context.firstname]] [[$Context.lastname]]

new_contactid value is not setting , above customerid is working and setting value in the lookup which is already prewritten in the Action Call.

I need to copy the contact lookup from the USD context but it is not working for new_contactid. Any USD Expert know the scriptlet to Set the lookup value in USD ?