Error in odd spot

I'm trying to debug an error I'm getting:

"Catchable fatal error: Object of class mysqli_result could not be converted to string in /home/dsnook/public_html/SecretSanta/scramble.php on line 69" Line 69 is :$sql="UPDATE users SET GivingGroupNum='$idquery' WHERE Email='$giver'"; and line 38 is: $randnum=rand(0, ($count-1));

So I try to put a var_dump of the variable causing the problem. After I add the var_dump and run it again I get a timeout error for line 38.

This confuses the hell outa me since I change nothing anywhere near or having to do with line 38. Which is where I get the rand value. Below is my entire code for the page.

    <?php
session_start();
    require('./include/config.inc.php');
    if(!isset($_COOKIE['email']))
        include('./include/header.html');
    else
        include('./include/header2.html');


    $gname=$_SESSION['gname'];
    $orderarray=array();
    $gmemberarray=array();
    $sql="SELECT GroupMember FROM santagroup WHERE GroupName='$gname'";
    $gmemberquery=mysqli_query($link, $sql);
    echo "<br><br>";

    foreach($gmemberquery as $person){
        $gmemberarray[]=$person;
    }

    //*********************************************************************************************************

    //***************************************************************************************************
    $neworder=array();
$xcount=count($gmemberarray);
//fill the array with numbers and a setting of false *hasn't been used*
while($xcount>=1){
    //$orderarray[($xcount-1)]=arrray();
    $orderarray[($xcount-1)][0]=($xcount);
    $orderarray[($xcount-1)][1]=false;
    $xcount--;
    //echo "<br>OrderArray: ".$orderarray[$xcount][0];
}
$xcount=count($gmemberarray);
$count=$xcount;
while($xcount>=1){
    R:
    $randnum=rand(0, ($count-1));

    $rand2=$randnum+1;
    if($orderarray[$randnum][1]==true) //If it's already been used get a different number
        goto R; //otherwise try again
    if($xcount!=($randnum+1)){ //if it's not equal to itself
        $neworder[($xcount-1)]=($randnum+1);
        $orderarray[$randnum][1]=true;
        //echo "<br><br>Neworder ".$xcount.": ".$neworder[($xcount-1)];
    }
    else
        goto R; //otherwise try again
    $xcount--;

}
$xcount=count($gmemberarray);
while($xcount>=1){
    //echo "<br>xcount: ".$xcount;
    $person=$neworder[$xcount-1];
    $giver1=$gmemberarray[$xcount-1];
    $giver=reset($giver1);
    $receiver=reset($gmemberarray[$person]);
    //$receiver=reset($receiver1);
    echo "<br>Groupname: ".$gname."   GiverEmail:  ".$giver."    ReceiverEmail: ".$receiver;
    $sql="INSERT INTO santaset (GroupName, GiverEmail, ReceiverEmail) VALUES ('$gname', '$giver', '$receiver')";
    $insertquery=mysqli_query($link, $sql);

    $sql="SELECT GroupSetID FROM santaset WHERE GiverEmail='$giver' AND ReceiverEmail='$receiver'";
    $idquery=mysqli_query($link, $sql);

    //var_dump($idquery);
    $sql="UPDATE users SET GivingGroupNum='$idquery' WHERE Email='$giver'";
    $setinfo=mysqli_query($link, $sql);
    $sql="UPDATE users SET ReceivingGroupNum='$idquery' WHERE Email='$receiver'";
    $setinfo=mysqli_query($link, $sql);
    $xcount--;
}


?>