无法使用Golang在Firebase中搜索数字？

I have the following Firebase Structure and I use Firego to connect with Golang.

"Job":{
  "-Kd0G5mRrRCXlGJmIuD0" : {
    "CurrentDate" : 1487153684854,
    "CustomerId" : "-Kcgz7IpH0fbs4EXaELr",
    "CustomerName" : "David",
    "JobName" : "Maintanence",
    "JobNumber" : "101",
    "NumberOfTask" : "1",
    "Status" : "Active"
  },
  "-Kd0UwmSHRhHdPX8z2hl" : {
    "CurrentDate" : 1487157576818,
    "CustomerId" : "-Kcg6uppyD8yKznNXZd7",
    "CustomerName" : "John",
    "JobName" : "Cleaning",
    "JobNumber" : "101",
    "NumberOfTask" : "4",
    "Status" : "Active"
  }
}

My Job Struct:

type Job   struct {
    CustomerId      string
    CustomerName    string
    JobName         string
    JobNumber       string
    NumberOfTask    string
    Status          string
    CurrentDate     int64
}

I used the folowing code to search Jobname = "Maintanence"

err = dB.Child("Job").OrderBy("JobName").EqualTo("Maintanence").Value(&job)
if err!=nil{
    log.Println("Error:",err)
}
if len(job)==0{
   log.Println("map null:",job)
}else{
   log.Println("map not null:",job)
}

and it print:

map not null: -Kd0G5mRrRCXlGJmIuD0" : {
            "CurrentDate" : 1487153684854,
            "CustomerId" : "-Kcgz7IpH0fbs4EXaELr",
            "CustomerName" : "David",
            "JobName" : "Maintanence",
            "JobNumber" : "101",
            "NumberOfTask" : "1",
            "Status" : "Active"
          }

But when I trird to search for the Jobnumber = "101" using following code

err = dB.Child("Job").OrderBy("JobNumber").EqualTo("101").Value(&job)
if err!=nil{
   log.Println("Error:",err)
}
if len(job)==0{
   log.Println("map null:",job)
}else{
   log.Println("map not null:",job)
}

it print:

map null:{}

Why I can't search and print the JobNumber = "101" , when I was able to search and print JobName = "Maintanence" ?