Unable to create user from Amazon Chime

I am trying to create user using "CreateUser" function of Amazon Chime through javascript but I am getting "BadRequestException: Service received a bad request". Has anyone faced this issue?

const params = {
      AccountId: process.env.ACCOUNT_ID /* required */,
      Email: 'testuser@gmail.com',
      Username: 'TestUser',
      UserType: 'SharedDevice',
    };
chime.createUser(params, function (err, data) {
      if (err) console.log(err, err.stack); // an error occurred
      else console.log(data); // successful response
    });