Ok, lets try this:
Change this code in category_manage.php (row 66-70):
mysql_select_db($database_RemoteDatabase, $RemoteDatabase);
$query_rsShowCat = "SELECT productcategories.CategoryName, productsubcategories.SubCategoryMainCategory, productsubcategories.SubCategoryName FROM productcategories, productsubcategories";
$rsShowCat = mysql_query($query_rsShowCat, $RemoteDatabase) or die(mysql_error());
$row_rsShowCat = mysql_fetch_assoc($rsShowCat);
$totalRows_rsShowCat = mysql_num_rows($rsShowCat);
---------------
to this:
mysql_select_db($database_RemoteDatabase, $RemoteDatabase);
$query_rsShowCat = "SELECT `productcategories`.`CategoryName` , `productsubcategories`.`SubCategoryMainCategory` , `productsubcategories`.`SubCategoryName` , `productsubcategories`.`SubCategoryID` FROM `RemoteDatabase`.`productsubcategories` INNER JOIN `RemoteDatabase`.`productcategories` ON (`productsubcategories`.`CategoryName` = `productcategories`.`CategoryID`) GROUP BY `productsubcategories`.`SubCategoryName`";
$rsShowCat = mysql_query($query_rsShowCat, $RemoteDatabase) or die(mysql_error());
$row_rsShowCat = mysql_fetch_assoc($rsShowCat);
$totalRows_rsShowCat = mysql_num_rows($rsShowCat);
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Im not sure about your field name etc., so i guess you will get some errors maybe. :)
If the insert of Main and Sub categories is working, then you can skip the repeate region of the different categories. Main thing is that the insert is working. :)