retrieving the value of a field in business process flow

for retrieving the value of fields from the business process field i have used this code. if condition qualifies but error is thrown when i try to fetch value of the field using getvalue(). why, can anybody explain? 

Note:field is an optionset

function clearfields()
{
if(Xrm.Page.getControl(header_process_customersatisfactioncode)!=null )
{
var val= Xrm.Page.getControl(header_process_customersatisfactioncode).getAttribute.getValue();
if(val==1 || val==2)
{
alert('satisfied/dissatisfied');
}
}
}