Error response when invoking App Initiated Conversation

Summary

Getting an error response from Skill/Digital Assistant when triggered via App Initiated Conversation

Content

 Hello Gurus -

   I am doing a proof-of-concept for App Initiated Conversation. I believe I have all setup correctly

• Twillio Account
• Twillio Channel
• Application Configuration
• Create Digital Assistant
• Event in the Skill

I am successfully receiving the text message by invoking the Application endpoint via Postman with the following request body:

{
  "userId" : "+639998166XXX",
  "messagePayload" : {
    "type" : "application",
 "payloadType" : "InitGreeting",
 "skillName" : "AppInitConvo",
 "channelName" : "NVD_TWILIO_SMS"
  }
}

But, the text message I am getting is the standard error message "Oops I'm encountering a spot of trouble. Please try again later..."