PHP Isset: If Condition Not Working

I'm having a problem getting my PHP IF condition to work which also involves issets. This is how the code is supposed to function on all conditions:

(It's basically a leaderboard, so I'm trying to get the fastest race time out of Single Player and Multiplayer modes no matter what.) I put the conditions below also numbered throughout the statement to understand where the problem is.

1. 
   

   If a user completes a SP race only, display the SP race time: (Condition works.)

   
   


2. 
   

   If a user completes a MP race only, display the MP race time: (Condition works.)

   
   


3. 
   

   If a user completes both modes with a faster MP race than SP race, show the faster MP race time. (Condition doesn't work.)

   
   


4. 
   

   If a user completes both modes with a faster SP race than MP race, show the faster SP race time. (Condition doesn't work.)

   
   

Code: http://ift.tt/UldW8M

I've tried changing and debugging all of my variables, but both modes will not get the fastest race time. My code always will display the slowest race time with #3 and #4.

Edit:

<?php

// Output the XML
$SP = simplexml_load_string($xml);
$MP = simplexml_load_string($xml1);
var_dump($SP);
echo "<br>";
var_dump($MP);
//I dont know if this line will cause any trouble yet...
$playertime = $world['eventDuration']; 
if (isset($SP->worldLeaderboard) && !isset($MP->worldLeaderboard)) 
{
  //we just have SP
  $worldboard = $SP;
  $mode = 'SP';
} 
else if (!isset($SP->worldLeaderboard) && isset($MP->worldLeaderboard)) 
{
  //we just have MP
  $worldboard = $MP;
  $mode = 'MP';
}
else if( isset($SP->worldLeaderboard) && isset($MP->worldLeaderboard))
{
  // we have both
  // worldboard ?
  // mode ?
  $milli = $SP->worldLeaderboard['eventDurationMilliseconds'];
  $milli1 = $MP->worldLeaderboard['eventDurationMilliseconds'];
  $variable = $SP->worldLeaderboard['eventDuration'];
  $variable1 = $MP->worldLeaderboard['eventDuration'];
  if($variable < $variable1)
  {
      $playertime = $variable;
      $worldboard = $SP;
      $mode = 'SP';
  } 
  else
  {
      $playertime = $variable1;
      $worldboard = $MP;
      $mode = 'MP';
  }

}
else
{
  // we have no XML...
}
?>

*XML:

    object(SimpleXMLElement)#3 (1) { 
    ["worldLeaderboard"]=> object(SimpleXMLElement)#5 (2) { 
        ["@attributes"]=> array(11) { 
            ["eventId"]=> string(2) "20" 
            ["eventType"]=> string(1) "2" 
            ["eventMode"]=> string(1) "1" 
            ["eventDurationMilliseconds"]=> string(6) "213622" 
            ["eventDuration"]=> string(11) "0:03:33.622" 
            ["createdDate"]=> string(31) "2014-07-21 00:53:35.0 GMT-00:00" 
            ["createdDateStr"]=> string(10) "2014/07/21" 
            ["personaName"]=> string(14) "GT544T4T34T4T3" 
            ["make"]=> string(15) "CAR_MANU_NISSAN" 
            ["carName"]=> string(17) "CAR_MDL_SILVIAS15" 
            ["rank"]=> string(1) "1" 
        } 

        ["persona"]=> object(SimpleXMLElement)#6 (1) { 
            ["@attributes"]=> array(5) { 
                ["personaName"]=> string(14) "GT544T4T34T4T3" 
                ["level"]=> string(1) "3" 
                ["image"]=> string(2) "19" 
                ["statusMessage"]=> string(0) "" 
                ["defaultPersona"]=> string(4) "true" 
            } 
        } 
    } 
} 
object(SimpleXMLElement)#2 (1) { 
    ["worldLeaderboard"]=> object(SimpleXMLElement)#5 (2) { 
        ["@attributes"]=> array(11) { 
            ["eventId"]=> string(2) "20" 
            ["eventType"]=> string(1) "1" 
            ["eventMode"]=> string(1) "1" 
            ["eventDurationMilliseconds"]=> string(6) "226126" 
            ["eventDuration"]=> string(11) "0:03:46.126" 
            ["createdDate"]=> string(25) "2014-07-21 00:43:23.0 GMT" 
            ["createdDateStr"]=> string(10) "2014/07/21" 
            ["personaName"]=> string(14) "GT544T4T34T4T3" 
            ["make"]=> string(15) "CAR_MANU_NISSAN" 
            ["carName"]=> string(17) "CAR_MDL_SILVIAS15" 
            ["rank"]=> string(1) "1" 
        } ["persona"]=> object(SimpleXMLElement)#6 (1) { 
            ["@attributes"]=> array(5) { 
                ["personaName"]=> string(14) "GT544T4T34T4T3" 
                ["level"]=> string(1) "3" 
                ["image"]=> string(2) "19" 
                ["statusMessage"]=> string(0) "" 
                ["defaultPersona"]=> string(4) "true" 
            } 
        } 
    } 
}