How do I retrieve Associated Employee in custom script in SAP Cloud studio ?

[nsetab]

I have created a Business object and one of the elements is an association to Employee  : -

[Label("EmployeeID")] element EmployeeID : EmployeeID;
association ToEmployee to Employee;

So I am not able to retrieve the employee in my custom script using the below code : -

var retrieveEmployee=BusinessPartner.Retrieve(this.ToEmployee.UUID);

The error is UUID does not exist.

Help.