Canadian addresses using the "North American Address Locator"

[HubertLo]

Using the sample codes given in http://resources.arcgis.com/en/help/silverlight-api/samples/start.htm#AddressToLocation I have changed the REST URL to point to that of the "North American Address Locator".

http://www.arcgis.com/home/item.html?id=919dd045918c42458f30d2c85d566d68
http://tasks.arcgisonline.com/ArcGIS/rest/services/Locators/TA_Address_NA_10/GeocodeServer

I find the web service is smart enough to recognize whether the address in Canada or US. However all the Canadian address return multiple results, some is correct whether others are not. Do I need to input some of the "Address Fields" in certain way to make the Canadian addresses work properly? How do you put the Canadian postal code (eg. L3Y 9C3) into the Zip or Zip4 fields? What kind of input is the Country field expecting?