Template Error: Instance of Fn: :Getatt References Undefined Resource Eventhandlerlambdafunction

Can anyone help me find what's wrong?

I'm importing this cloudformation resources in my serverless yml. This is my function config:

Resources:
  eventHandler:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: eventLambda/
      Handler: dist/app.eventHandler
      Runtime: nodejs12.x
      FunctionName: eventHandler

This where I'm referencing it:

eventSourceRule:
    Type: 'AWS::Events::Rule'
    Properties:
      Name: eventSourceRule
      EventBusName: omnibus-${self:custom.stage}
      EventPattern: |
        {
          "source": ["op.api"]
        }
      RetryPolicy:
        MaximumRetryAttempts: 5
        MaximumEventAgeInSeconds: 900
      DeadLetterConfig:
        Type: SQS
        QueueLogicalId: EBRuleDLQ
      Targets:
        - Arn:
            Fn::GetAtt:
              - 'EventHandlerLambdaFunction'
              - 'Arn'
          Id: 'eventSourceRule'

Notice that I've already tried eventHandler and EventHandler and none of these worked. That's the error I'm receiving:

The CloudFormation template is invalid: Template error: instance of Fn::GetAtt references undefined resource EventHandlerLambdaFunction