Hi Puneet,
I'd recommend to declare the toEmployee association within the declaration of the laptop details node. Something like
node lapempdet [0,n] {
element EmployeeID : .....
element ....
association toEmployee to Employee;
};
Additionally you should check like Ludger said whether your List Pane (your UI table), that is the List "DataList" in your DataModel on the left side is bound to the node "lapempdet" on the right side.
Regards,
Leonid