in the parent list, you are using the league name column, but you mention the TeamDiv?
<option value="<?php echo $row_Parent['league_name']?>"><?php echo $row_Parent['league_name']?></option>
also the Parent recordset looks nothing like what you say in your message
anyway, you have the child recordset. In the create dynamic array behavior, set the parent ID to league_name (or use TeamDiv, but only if that is the column being used as the value for the parent list, as it stands right now, you are using league_name as the value for the parent list, so in the create dynamic array, it should be used as the parant ID column)
for the child ID and child name, use the team name column
in the populate list from array behavior, set the parent list to parent list and the child list to the child list.