Dear,
From the language, we presume that u have sold the goods to karnataka dealer.
Sales Tax/ VAT is on goods. The movement of goods is important for charge of Sales Tax. If the final destination is at karnataka where the goods are delivered then it is inter-state sale.
For practical accounting convinence, take the invoice from Karnataka dealer/party, where the goods are delivered.
If we assume that u have sold the goods to A.Pdealer, and who again sold it to Karnataka, then for u it is VAT sales.