ListBox Sorting issue (inaccurate)

I am having a problem with sorting a multi-column ListBox. For simplicity, let's say I only have 3 columns: Id, Score, and TotalPoints. I have implemented a Compare method from the IComparer interface that looks like this:

public int Compare(object x, object y)

{

int compareResult;

ListViewItem listviewX, listviewY;

// Cast the objects to be compared to ListViewItem objects

listviewX = (ListViewItem)x;

listviewY = (ListViewItem)y;

// Compare the two items

// Calculate correct return value based on object comparison

if (OrderOfSort == SortOrder.Ascending)

// Ascending sort is selected, return normal result of compare operation

return compareResult;

else if (OrderOfSort == SortOrder.Descending)

// Descending sort is selected, return negative result of compare operation

return (-compareResult);

else

// Return '0' to indicate they are equal

return 0;