shopify lightspeed integration not working on some products

[Tash250]

Hi there,  I currently run 2 bricks & mortar stores that are both online with Lightspeed POS in-store and Shopify.  Sometimes our inventory between Lightspeed & Shopify is incorrect on some of our products, which is allowing customers to place an order for product that we don't have in store...how is this happening??  Help pls!!!