The CDXZipStream uses the "ResultsQuality" property of MapPoint to determine if a value should be returned for the CDXRouteMP and CDXLocateMP functions.  There are 4 values for ResultsQuality.

1 - The first result is a good match to the method criteria
2 - At least the first two results are good matches, but it is not clear which one was intended
3 - None of the results is a good match to the method criteria, but the results are the best available
4 - No results

CDXRouteMP will return results if the ResultsQuality values 1 or 2 are returned for both addresses.  3 and 4 will return the error above.

The CDXLocateMP function will only return results if an exact match is returned (1).  If the ambiguous flag is set it will also return results from the first returned entry if at least two good results are found (2).  ResultsQuality values of 3 and 4 will return the error above.

There are instances where an address is valid but it is simply not covered by MapPoint.  One workaround for this is to substitude a known good address or the zip code for the area.  If you know the latitude and longitude, use our reverse geocoding function in CDXLocateMP to get a valid address and use this as a substitute.