doesn't work with dart

[huanmoon]

this plugin looks SOOOOO GREAT but sadly when I'm trying to use dart it doesn't work at all

"lsp.autocompleteDetails": true,
    "lsp.formatOnSave": false,
    "lsp.ignoreMessages": "LS message1 to ignore|LS message 2 to ignore|...",
    "lsp.ignoreTriggerCharacters": "completion,signature",
    "lsp.server": "dart=dart language-server, c++=clangd",
    "lsp.tabcompletion": true,

this is my config but it doesn't work at all thanks in advance!!! =)