What problem can be in url based database connection in slick with playframework?

Play Framework
1

I am using this config in play application.conf with direct slick library not with play-slick.

in play application.conf

mydb {
  dataSourceClass = "slick.jdbc.DatabaseUrlDataSource"
  properties = {
    driver = "slick.driver.PostgresDriver$"  // not working
    url = "postgresql://postgres:admin@localhost:5432/postgres"
  }
}

But it is not working while instead this is working-

mydb {
  dataSourceClass = "slick.jdbc.DatabaseUrlDataSource"
  properties = {
    driver = "org.postgresql.Driver" //ok
    url = "postgresql://postgres:admin@localhost:5432/postgres"
  }
}