php - Session Array not working -

so i'm creating array in session reason when try add stuff it, no longer array. i'm not sure happening.

adding item

if(!isset($_session['printsid']) && !isset($_session['printsnum'])){     $_session['printsid']=array();     array_push($_session['printsid'],$_get['itm']);     $_session['printsnum']=array();     array_push($_session['printsnum'],$_get['num']);     header('location: google.com'); } else{     array_push($_session['printsid'],$_get['itm']);     array_push($_session['printsnum'],$_get['num']);     header('location: http://www.repmofbla.com/simmonsredone/');     } 

getting item

if(isset($_session['printsnum'])){        $cartitems = array_sum($_session['printsnum']);          $cartitems += sizeof($_session['artwork']); }  else{      $cartitems = sizeof($_session['artwork']); } 

any great. thank guys :)

(i'm not best php know there more efficient way this. respect please)

more details: parts on different pages. what's weird when first upload script works. use add script quits working , array's no longer "exist", if reupload script works again. it's weirdest thing i've ever encountered.

that's because, trying redirect different domain. redirecting different domain doesn't carry session forward.