You are trying to left join the CUST and COST fields with the Inv_Sales_Temp table. But there is no such filed names exist in Inv_Sales_Temp. You need a key field, so that left join will work. You can use alias names to left join the table.
Cust as IVCost.
But you need to explain what is the error and what you are trying to achieve. It will be helpful to give you the solution.