issue with making custom loot in structure on mcreator 2021.1

Hello, I have a problem with the command block. I wanted to create a custom loot in a dungeon following a guide. I did everything according to the guide. But the problem started with the command block. When I entered and edited this command /setblock ~ ~1 ~ minecraft:chest{LootTable:"modname:type/loottable"} destroy, after I activate command block and nothing happen, this command was not highlighted; for example, when you place a slash, it turns yellow and commands are shown. Please help me with the command block. (I enabled cheats in the world and edited in creative mode) Good luck!