功能没有给出期望的结果

I am having a php function:

<?php
function find_senior($mylevel, $sender){
    global $class_database;
    global $g_level1;
    global $g_level2;
    global $g_level3;

$sponsor=$class_database->getdata("sponsorid", "id='$sender' AND gift_level > '$mylevel'", "user");
$sponsor2=$class_database->getdata("sponsorid", "id='$sender'", "user");
    if(strlen($sponsor) > '0'){
        if($mylevel < $g_level1){
        return array("id"=>"1", "amt"=>$g_level1, "lvl"=>$g_level1);    
        }
        elseif($mylevel < $g_level2){
        return array("id"=>"1", "amt"=>$g_level2, "lvl"=>$g_level2);    
        }
        elseif($mylevel < $g_level3){
        return array("id"=>"1", "amt"=>$g_level3, "lvl"=>$g_level3);    
        }
    }
    elseif(strlen($sponsor) <='0' && strlen($sponsor2) <='0'){
        if($mylevel < $g_level1){
        return array("id"=>"1", "amt"=>$g_level1, "lvl"=>$g_level1);    
        }
        elseif($mylevel < $g_level2){
        return array("id"=>"1", "amt"=>$g_level2, "lvl"=>$g_level2);    
        }
        elseif($mylevel < $g_level3){
        return array("id"=>"1", "amt"=>$g_level3, "lvl"=>$g_level3);    
        }   
    }
elseif(strlen($sponsor) <='0' && strlen($sponsor2) >'0'){
    find_senior($mylevel, $sponsor2);
    }

}

?>

it should return as array when we do var_dump()

$array=show("100", "2");
var_dump($array);

But it is returning only :

NULL

Where is the error may be ? I am very new to php, please try to solve this puzzle, I tried a lot, but may be for my limited knowledge I am ubnable to solve it

It should be:

class myClass{
function show($g_level1, $id){
return array("id"=>$id, "amt"=>$g_level1, "lvl"=>$g_level1);
}
}

Now create instance of that class:

$instance = new myClass();
$instance->show("100", "2");