Connect serverless to mongo VPC

Serverless Framework
1

Hello, I have the following serveless.yaml file:

service: mongo-serverless

provider:
  name: aws
  runtime: nodejs4.3
  stage: ${opt:stage}
  profile: ${self:custom.profiles.self:provider.stage}
 
  iamRoleStatements:
    - Effect: Allow
      Action:
        - dynamodb:*
      Resource: "*"
    - Effect: Allow
      Action:
        - ec2:CreateNetworkInterface
        - ec2:DescribeNetworkInterfaces
        - ec2:DetachNetworkInterface
        - ec2:DeleteNetworkInterface
      Resource: "*"
    - Effect: Allow
      Action:
        - s3:*
      Resource: "*"
  vpc:
    securityGroupIds:
      - sg-xxxx
    subnetIds:
      - subnet-xxxx

functions:
  graphql:
    handler: build/main.graphql
    timeout: 12
    events:
      - http:
          path: graphql
          method: post
          cors: true

both security group and subnets exists on my VPC but i am not able to make the serverless connect to mongo and get this error in the logs

module initialization error: Error

graphql function - is there a way to further test what is going on?