Uploading file in PHP returns nothing when file size is big -

<?php //max size of 2 mb   define('max_file_size','2000000');//2 mb  $allowed_file_types=array('image/jpg','image/png','image/jpeg'); //var_dump($_files['file_to_upload']); if($_server['request_method']=='post'){     if(isset($_post['action'])){         if($_post['action']=='upload_image'){             //if($_files['file_to_upload']['error']){              //}             if(isset($_files['file_to_upload'])){                 $file_arr=$_files['file_to_upload'];                 $check=false;                 echo $file_arr['type'];                 //for allowing image type                  foreach($allowed_file_types $type){                     if($file_arr['type']==$type){                         $check=true;                     }                 }                  if($check){                     //checking size limit                     if($file_arr['size']>max_file_size){                         echo "<p class='warning'>the file size above limit. optimize image , upload again.</br>your file size:".round(($file_arr['size']/1000000),2)."mb<br/>allowed file size: ".round((max_file_size/1000000),2)."mb</p>";                     }else{                         upload_form($file_arr);                     }                 }else{                     echo "<p class='warning'>".$file_arr['type']." type of file not allowed upload</p>";                 }              }         }     } } 

i using code information file uploading form. happens when select file greater 2.7/3 mb var_dump have used on $_files return null. working on other files less size. proper array $_files. may causing happen? suggestions?

btw php.ini max_upload_size==65m