Compraiser uses several of the most popular geocoding sites available to validate addresses. However, sometimes a valid address is not recognized. If you are having trouble getting an address to work, try the following.
Double check the zip code.
Use street coordinates instead of street names.
Shift one of the coordinates slightly. A location very close should produce a solution very similar. Make sure that you don't shift the coordinates into a location that has very different types of properties from the original location.
Sometimes there are dead spots where too few properties have sold to give meaningful feedback.