Hello Ladimaco,
GetTopNRanker & GetTopNRanking both method are written on the different concept. In GetTopNRanker method, you will only find the top score of user made in the game but in GetTopNRanking method, you will find the list of scores in sorted format.
For example: We have a list of user A & B in the leaderboard in which A has scored 400, 200 and B scored 300. In this when you call GetTopNRanker method, you will find only two records where A is on 1st position and B on second. Where in GetTopNRanking method, you will find three position in which A is on first and third and B is on second.
In your case, you find 1 count because of only one user have scored in the game. You can save the scores for four to five users & you will find the desired result. Please check & let us know if it helps.
Thanks,
Himanshu Sharma