This isn't working

[Icandie]

In op skyblock I placed a slime spawner and it's not working(Y25toY35)I asked dragon boy and he said that I need to build a dark room but when I built it it still doesn't work I than asked him why but he doesn't know if anyone knows why please tell me

 

[Pinoy]

In op skyblock I placed a slime spawner and it's not working(Y25toY35)I asked dragon boy and he said that I need to build a dark room but when I built it it still doesn't work I than asked him why but he doesn't know if anyone knows why please tell me

Levels 0 through 39 in specificchunks they spawn and any light level... then if you island is
Swamp biomes they levels 51 through 69 thats all i know..

 

[Haoiscoll]

Slimes only spawn on grass and water, so make sure you have these blocks around your spawner. Also light levels affect the spawning.