Join With Camlquery for Lookup Column Field

Question

there are 3 List on My Scenario :

1) Tasks : Columns like this :

(Column Name)  Title  
            --------------------------
               TitleTest
               TitleTest2

2) List1 : Column like :

   (Column Name)Title  test(Discription Type)     tasklook(Lookup TasksList)
              -----------------------------------------------
               test1   blah blah                   TitleTest
               test2   lorem ispum                 TitleTest2

3) List 2 : Column like :

  (Column Name)Title   reflist1(Lookup frm List1)
              -----------------------------------------------
               test1   test1        
               test2   test2     

Camlquery with Join:

      SPList olistbug = _web.Lists["List2"];
      SPList first = _web.Lists["List1"];
      SPQuery query1 = new SPQuery();
      query1.Query = @"<OrderBy><FieldRef Name='Title' Ascending='True' /></OrderBy>";

  // working query when use test column from list1.          
     query1.ProjectedFields = @"<Field Name='reftest' Type='Lookup' List='List1' ShowField='test' />";
     query1.Joins = @"<Join Type='LEFT' ListAlias='List1'><Eq><FieldRef Name='reflist1' RefType='Id' /><FieldRef List='List1' Name='ID' /></Eq></Join>";
     query1.ViewFields = @"<FieldRef Name='Title' /><FieldRef Name='reflist' /><FieldRef Name='reftest' />";
     query1.RowLimit = 150000;   
     SPListItemCollection coll = olistbug.GetItems(query1);

but when use tasklook as a Its throwing Error.

       query1.ProjectedFields = @"<Field Name='reftasklook' Type='Lookup' List='List1' ShowField='tasklook' />";
       query1.Joins = @"<Join Type='LEFT' ListAlias='List1'><Eq><FieldRef Name='reflist1' RefType='Id' /><FieldRef List='List1' Name='ID' /></Eq></Join>";
       query1.ViewFields = @"<FieldRef Name='Title' /><FieldRef Name='reflist' /><FieldRef Name='reftasklook' />";