Groovy Script to update SR status when a Primary Contact adds a message

Summary:

In the Implementing HR Help Desk guides I found a Groovy Script to update the SR status when the Primary Contact adds a message on to the SR, I've created this but it isn't working, has anyone managed to get this working?

How can I automatically update a help desk request status after a customer response?

Groovy Script is:

def parentSR = ServiceRequest
def msgSource = SourceCd
def msgChannel = ChannelTypeCd
def parentStatus = ServiceRequest?.StatusCd
def msgType = MessageTypeCd

if (msgSource =='ORA_SVC_INBOUND_MSG' && msgChannel =='ORA_SVC_EMAIL' &&
msgType == 'ORA_SVC_CUSTOMER_ENTRY' && ParentMessageId !=null)

parentSR.setAttribute('StatusCd', 'CUST_RESPOND')

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