How to connect github repo with aws using cdk?

Im learning aws cdk and trying to make a code pipeline.

i created personal access key on github and saved it on aws secret manager.

then in my cdk stack i wrote`

pipeline.addStage({
      stageName:"Source",
      actions:[
        new CodePipelineAction.GitHubSourceAction({
          actionName: 'CheckOut',
          owner: 'Mahmood787',
          repo: "aws-pipeline",
          oauthToken: cdk.SecretValue.secretsManager('github2'),
          output:sourceOutput,
          branch:"master" 
        })
      ]
    });

on cdk deploy im getting this error

Webhook could not be registered with GitHub. Error cause: Invalid credentials [StatusCode: 401, Body: {"message":"Bad credentials","documentation_url":"https://docs.github.com/rest"}]

is there anything im missing?