WenDynpro jave problem

I'm doing one of the example from tech ed 2008 java web dynpro in SAP Netweavre CE system. In that I cretaed two table one with slaes order and another with item line details. In the jave code when I write the code as follows the system is showing an error

public void wdDoInit()

{

//@@begin wdDoInit()

// Get a reference to the SalesOrders context node

ISalesOrderNode soNode = wdContext.nodeSalesOrder();

//Create two new Sales Order elements and immediately add them

//to the node collection

ISalesOrderElement soE11 = soNode.createAndAddSalesOrderElement();

ISalesOrderElement soE12 = soNode.createAndAddSalesOrderElement();

soE11.setLongtext("Printer Supplier");

soE11.setOrderNo(1000);

soE11.setSalesDate(new Date(System.currentTimeMillis()));

soE11.setSalesRep("Dinesh Ghanta");

soE12.setLongtext("Network Equipment");

soE12.setOrderNo(1001);

soE12.setSalesDate(new Date(System.currentTimeMillis()));

soE12.setSalesRep("Ned Seagoon");

// Create the LineItems node instances for each SalesOrders element

** ILineItemsNode liNode1 = soE11.nodeLineItems();**

** ILineItemsNode liNode2 = soE12.nodeLineItems();**

// Create new elements for each LineItems node,

// set the attribute values and add them to the nodes

//@@end

}

//@@begin javadoc:wdDoExit()

The system is saying that there is a type mismatch error on both the lines where I'm creating the items. Can you please help me here...am I msising something.