I give my goomy rare candy  from lvl 98 to lvl 99 and evolve into sliggoo but when i put another rare candy on it, it turn lvl 100  without evolving .Can you fix the issue? You can check my gameplay there is no  evolve sign when reach lvl 100

To evolve Sliggoo you have to be on a map with rainy weather on it.

Since your Sliggoo is level 100 now you have to use a mysterious candy to evolve it since a mysterious candy will evolve a pokemon at level 100 as long as you meet the requirements for that evolution (Rainy Weather on the map for Sliggoo).

You can purchase mysterious candies in all four department stores (Celadon, Goldenrod, Lilycove, Veilstone) for 5k pokedollars, for 2 PvE coins at PvE Coin Masters or for 1 PvP coin at PvP Coin Masters.