无法使用mgo从MongoDB通过ObjectId获取数据

I have a PersonalAccount type as

type PersonalAccount struct {
        ID        bson.ObjectId   `json:"id" bson:"_id,omitempty"`
}

then I get a marshaled PersonalAccount through an HTTP request, and the data is unmarshaled successfully and when I check the ID type. It is a bson.ObjecID

The problem is when I try the code below:

var m PersonalAccount = unmarshaledAccount
mgo.DB("dbname").C("colname").FindId(m.ID)

It returns an error that says it is not found.

I have also tried:

var m PersonalAccount = unmarshaledAccount
mgo.DB("dbname").C("colname").Find(bson.M{"_id": m.ID})

but with no luck.