makemigrations reponses No changes detected when app_label is specified

I have 2 mysql databases and I want to create a new model to the second one (analysis_db), but after running makemigrations, it says "No changes detected". Here are my codes

In settings.py ( I added myapp to INSTALLED_APPS )

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': DB_DEFAULT_NAME,
        'USER': DB_USER,
        'PASSWORD': DB_PASSWORD,
        'HOST': DB_HOST,
        'PORT': '',
        'OPTIONS': {
            'sql_mode': 'traditional',
        }
    },
    'analysis_db': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': DB_ANALYSIS_NAME,
        'USER': DB_USER,
        'PASSWORD': DB_PASSWORD,
        'HOST': DB_HOST,
        'PORT': '',
        'OPTIONS': {
            'sql_mode': 'traditional',
        }
    }
}
DATABASE_ROUTERS = ['my_project.routers.TestRouter']

In routers.py

class TestRouter:
    """
    A router to control all database operations on models in the
    auth application.
    """
    def db_for_read(self, model, **hints):
        if model._meta.app_label == 'analysis_data':
            return 'analysis_db'
        return None

    def db_for_write(self, model, **hints):
        if model._meta.app_label == 'analysis_data':
            return 'analysis_db'
        return None

    def allow_relation(self, obj1, obj2, **hints):
        if obj1._meta.app_label == 'analysis_data' or \
           obj2._meta.app_label == 'analysis_data':
           return True
        return None

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        if app_label == 'analysis_data':
            return db == 'analysis_db'
        return None

In models.py

class TestModel(models.Model):
    id = models.AutoField(primary_key=True)
    val1 = models.IntegerField()
    val2 = models.IntegerField()

    class Meta:
        app_label = 'analysis_data'
        db_table = 'test_table_on_db'

However, if I remove app_label = 'analysis_data' from models.py, and run makemigrations again, it works, but the table was created on the default db. Does anybody got the same problem?

Thanks :)