question

You have to adjust the pull code to read the label as a string. Currently they are assigned to an integer variable, in which case any string evaluates to 0. So later in the code, the number 0 is compared to the other item's labels, resulting in no match.

Don't forget to also change the reset value of the 'MatchedOrder' label on the combiner. The code below assumes an empty string to be the default value.

/**Matching Orders*/
string MatchedOrder = current.MatchedOrder;
if (MatchedOrder != "") {
    //We previously matched an item so pull the matching order from the other queue
    if (item.Order == MatchedOrder) {
        current.MatchedOrder = "";
        return 1;
    }
    return 0;
}

string Order = item.Order;
//Search the opposite queue for the same order
int otherPort = port % 2 + 1; //Grab the other port rank so we look at the other queue
treenode queue = current.as(Object).inObjects[otherPort];
for (int i = 1; i <= queue.subnodes.length; i++) {
    if (queue.subnodes[i].Order == Order) {
        //Found a matching order, save the order on a label
        current.MatchedOrder = Order;
        //Now pull the item that just entered the original queue
        return 1;
    }
}
//No matches, pull nothing
return 0;