php - Join in Doctrine not working -

I implemented the principle in CodeIgniter. I used the unit sections PdContact and PdSubject and placed under the unit folder under the model folder. I have used the following code to join tables:

  $ qb = $ this-> Em- & gt; CreateQuerybuilder ('c') - & gt; Select ('PDCTTact') - & gt; LeftJoin ('PDSbackext', 'co', 'with', 'co.id = cid') - & gt; Setx result (20); $ Query = $ qb- & gt; GetQuery (); Return $ query- & gt; GetResult ();  

But this is not working please give a suggestion.