MODULE ERROR (3)

Error: Error running sql query: {SELECT Inventory.item_ID FROM Inventory LEFT JOIN Inventory_Lookup ON Inventory_Lookup.item_ID = Inventory.item_ID LEFT JOIN Inventory_Categories ON Inventory_Categories.category_ID = Inventory_Lookup.category_ID WHERE Inventory_Lookup.category_ID = }. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 14

File: /var/www/vhosts/spanwell.com/httpdocs/fw/core/core.class.php

Line: 176

Stack Trace:
#0 /var/www/vhosts/spanwell.com/httpdocs/fw/modules/inventory.class.php(325): Core::dbQuery('SELECT????????I...', 3)
#1 /var/www/vhosts/spanwell.com/httpdocs/displays/inventory/inventory.php(76): Inventory->totalInventoryByCategory()
#2 /var/www/vhosts/spanwell.com/httpdocs/displays/includes.php(78): include('/var/www/vhosts...')
#3 /var/www/vhosts/spanwell.com/httpdocs/templates/template-interior.php(119): include('/var/www/vhosts...')
#4 /var/www/vhosts/spanwell.com/httpdocs/fw/core/core.class.php(252): include('/var/www/vhosts...')
#5 /var/www/vhosts/spanwell.com/httpdocs/site(57): Core->displayPage('interior')
#6 {main}