Summing Columns

Question

SELECT  SI.vItemName, SI.iNos, SI.deAmount,TS.dInvoiceDate SUM(SI.tblSalesItem.orders) FROM tblSales TS
INNER JOIN tblSalesItem SI ON TS.iSalesID=SI.iSalesID GROUP BY  SI.vItemName, SI.iNos, SI.deAmount,TS.dInvoiceDate


ERROR IN SQL 2005
  Msg 102, Level 15, State 1, Line 7
Incorrect syntax near 'SI'.


PLEASE  CORRECT?