LDAP无法将用户添加到组

Question

I need add a user to the group.

package main

import (
    "fmt"
    "log"
    "crypto/tls"
    "gopkg.in/ldap.v2"
)

func main() {

    bindusername := "user"
    bindpassword := "pass"

    l, err := ldap.Dial("tcp", fmt.Sprintf("%s:%d", "ldap.example.com", 389))
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Connect dial")
    defer l.Close()

    // Reconnect with TLS
    err = l.StartTLS(&tls.Config{InsecureSkipVerify: true})
    if err != nil {
        log.Fatal(err)
    }

    err = l.Bind(bindusername, bindpassword)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Connect bind")

    modify := ldap.NewModifyRequest("CN=test-group,OU=,DC=,DC=,DC=")
    modify.Add("member", []string{"CN=test-user,OU=,OU=,OU=,DC=,DC=,DC="})


    err = l.Modify(modify)
    if err != nil {
        log.Fatal(err)
    }
}

But i can an errors: 2018/10/29 10:33:00 LDAP Result Code 53 "Unwilling To Perform": 00002147: SvcErr: DSID-031A12D2, problem 5003 (WILL_NOT_PERFORM), data 0.

If I change

modify.Add("member", []string{"CN=test-user,OU=,OU=,OU=,DC=,DC=,DC="})

to

modify.Add("description", []string{"test"})

, there is no error. Help, please.