lookup array shows no result

Question

i am building an apllication with mongoose and node.js that enables you to post, comment, and like both the posts and the comments. those are my schemas and the query that i am trying to built to send the user using the apllication all the posts, comments, likes to both the comment section and the post section.
tried to use lookup with mongoose to get comments (and to them likes),but the the pogram shows me no result as can you see: ( i checked by the way .)

comment.js

const commentSchema= 
    new mongoose.Schema({
      userID : {type: mongoose.Types.ObjectId, ref: "User",required: true },
      content : {type: String,required: true },
      date :{type : Date,default:()=>Date.now()} ,
  })
       module.exports=mongoose.model("comment",commentSchema)

likes.js

const LikesSchema= new mongoose.Schema({
    userID : {type: mongoose.Types.ObjectId, ref: "user",required: true },
    postCommentID : {type: mongoose.Types.ObjectId ,required: true } //can be both a comment or a post
})
module.exports=mongoose.model("likes",LikesSchema)

posts.js

const postSchema= new mongoose.Schema({
    userID : {type: mongoose.Types.ObjectId, ref: "User",required: true }, 
    content : {type: String,required: true },
    date : {type : Date,default:()=>Date.now()},
    commentsID :[{type:mongoose.Types.ObjectId, ref:'comment' }],
})
module.exports=mongoose.model("post",postSchema)

incomplete query

Query.js

post.aggregate(
    [
         {
             $lookup: {
                 from: 'likes',
                 localField: '_id',
                 foreignField: 'postCommentID',
                 as: '_likes'
             },
         },
       
        
          {
           //NOT WORKING
             $lookup: {
                 from: 'comment',
                 localField  : 'commentsID',
                 foreignField  : '_id',
                 as: 'comments'
             },
          },

         {
             $set: {
              
                 'likes': '$_likes.userID'
             }
         },
         {
             $project: {
                 '_likes': 0,
             }
         },
    ]
)

result: as can you see the comment section is empty.

  [{
    _id: new ObjectId("621fdff521935fad17cc27b5"),
    userID: new ObjectId("621ba7b84ade9cd7ebe7ef46"),
    content: 'new post',
    commentsID: [
      new ObjectId("621fe07c21935fad17cc29f9"),
      new ObjectId("621fe2b221935fad17cc2aef"),
      new ObjectId("621fe2ff21935fad17cc2b45"),
      new ObjectId("621fe83260288e8ee9db1d62"),
      new ObjectId("621fe9361ab243a8c2ebb0eb"),
      new ObjectId("621ff5d471b483d2f59ca493")
    ],
    date: 2022-03-02T21:21:57.660Z,
    __v: 0,
    comments: [],
    likes: [
      new ObjectId("621fe07c21935fad17cc29f9"),
      new ObjectId("621fe2b221935fad17cc2aef"),
      new ObjectId("621fe2ff21935fad17cc2b45")
]
  }
]