when we try to create sale, and add certain items, we are getting a message like this Stock not available, but stock available. Another symptom is that when the submit button is clicked to complete the sale, the page just flashes but remains on same Sale screen. I have enabled development mode and I get the error message below. I have also enabled logging=1 but not errors are shown in the error log.

A PHP Error was encountered Severity: Warning Message: Division by zero Filename: models/Site.php Line Number: 72 Backtrace: File: /home/deltexart/Inventory/app/models/Site.php Line: 72 Function: _error_handler File: /home/deltexart/Inventory/app/models/Site.php Line: 923 Function: calculateCost File: /home/deltexart/Inventory/app/models/Site.php Line: 262 Function: item_costing File: /home/deltexart/Inventory/app/models/admin/Sales_model.php Line: 71 Function: costing File: /home/deltexart/Inventory/app/controllers/admin/Sales.php Line: 265 Function: addSale File: /home/deltexart/Inventory/index.php Line: 273 Function: require_once A PHP Error was encountered Severity: Warning Message: Division by zero Filename: models/Site.php Line Number: 72 Backtrace: File: /home/deltexart/Inventory/app/models/Site.php Line: 72 Function: _error_handler File: /home/deltexart/Inventory/app/models/Site.php Line: 923 Function: calculateCost File: /home/deltexart/Inventory/app/models/admin/Sales_model.php Line: 86 Function: item_costing File: /home/deltexart/Inventory/app/controllers/admin/Sales.php Line: 265 Function: addSale File: /home/deltexart/Inventory/index.php Line: 273 Function: require_once