The validator doesn't check the set of elements in the feed. For example, if an XML document does't have a required element for the program, the validator will not detect this. As a result, the feed will not work in the partner program. Therefore, we recommend checking the XML document elements for compliance with the program's technical requirements.
There are several types of validation schemes available in the tool. Make sure that you selected the correct scheme. The Realty scheme is selected by default. Otherwise, you will see an error:
Line: 3 Position: 38 Details <detail>cvc-elt.1.a: Cannot find the declaration of element 'yml_catalog'.</detail>
You can also upload your own scheme using the other schemes button.