title: orderByChild query not working as expected in ionic 3, angularfire 2
body: <p>i'm trying to print all the users that i have on my firebase using firebaselist.</p>
  
  <p>Decleration of angularfirelist </p>
  
  <pre><code>ProfileList:AngularFireList&lt;Profile&gt;
  </code></pre>
  
  <p>then in my service provider function. i'm calling my firebase like this. </p>
  
  <pre><code>result= this.database.list('/Profiles', ref =&gt; {
              ref.orderByChild('name').equalTo(Firstname)          
              return ref;
     });
  return result
  </code></pre>
  
  <p>and in the main body i'm calling this function like </p>
  
  <pre><code>this.data.SearchUser(Query).valueChanges().subscribe((profile)=&gt;{
              console.log("profiles are:",profile)
        })
  </code></pre>
  
  <p>and then this is my firebase database sutructure</p>
  
  <pre><code>chatapp-1759eaddclose
      Profiles
        LN6OnvZsj3XHZNurU2Tm86JVqm93
          DateOfBirth: 
             "2018-01-01"
          email: 
            "travelbuddy1114@gmail.com"
          last_name: 
            "riaz"
          name: 
            "raheel "
       l2hghReBkWOUCYZCy1yPUPbvHxi2
         DateOfBirth: 
            "2017-12-31"
         email: 
            "azharejaz45@gmail.com"
         last_name: 
            "Ejaz"
         name: 
            "Azhar"
  </code></pre>
  
  <p>i'm getting every profile that i have on my firebase account but i'm running a query on give me profile of every user that name matches with my entered name and the query part is not working, i tried to run it without query and simple returning ref and i'm getting same result as i'm getting with query. 
  can anyone please help me about why my query part is not working?</p>